Phthalazinone derivatives

ABSTRACT

A compound of the formula (I): 
     
       
         
         
             
             
         
       
     
     wherein:
 
A and B together represent an optionally substituted, fused aromatic ring;
 
D is selected from:
 
(i)
 
     
       
         
         
             
             
         
       
     
     where Y 1  is selected from CH and N, Y 2  is selected from CH and N, Y 3  is selected from CH, CF and N; and
 
(ii)
 
     
       
         
         
             
             
         
       
     
     where Q is O or S;
 
R D  is:
 
     
       
         
         
             
             
         
       
     
     wherein
 
R N1  is selected from H and optionally substituted C 1-10  alkyl;
 
X is selected from a single bond, NR N2 , CR C3 R C4  and C═O;
 
R N2  is selected from H and optionally substituted C 1-10  alkyl;
 
R C3  and R C4  are independently selected from H, R, C(═O)OR, where R is optionally substituted C 1-10  alkyl, optionally substituted C 5-20  aryl or optionally substituted C 3-20  heterocyclyl;
 
Y is selected from NR N3  and CR C1 R C2 .
 
R C1  and R C2  are independently selected from H, R, C(═O)OR, where R is optionally substituted C 1-10  alkyl, optionally substituted C 5-20  aryl or optionally substituted C 3-20  heterocyclyl; R C1  and R C2  together with the carbon atom to which they are attached may form an optionally substituted spiro-fused C 5-7  carbocylic or heterocyclic ring; and
 
when X is a single bond R N1  and R C2  may together with the N and C atoms to which they are bound, form an optionally substituted C 5-7  heterocylic ring;
 
and when X is CR C3 R C4 , R C2  and R C4  may together form an additional bond, such that there is a double bond between the atoms substituted by R C1  and R C3 .

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a divisional of U.S. patent application Ser. No. 11/550,004 filed on Oct. 17, 2006, which claims priority to U.S. Provisional Patent Application Ser. Nos. 60/728,050 filed on Oct. 19, 2005 and 60/822,663 filed on Aug. 17, 2006, and claims foreign priority to United Kingdom Patent Application No. 0521373.1 filed on Oct. 20, 2005. These applications are incorporated herein by reference in their entireties.

The present invention relates to phthalazinone derivatives, and their use as pharmaceuticals. In particular, the present invention relates to the use of these compounds to inhibit the activity of the enzyme poly (ADP-ribose)polymerase-1, also known as poly(ADP-ribose)synthase and poly ADP-ribosyltransferase, and commonly referred to as PARP-1.

The mammalian enzyme PARP-1 (a 113-kDa multidomain protein) has been implicated in the signalling of DNA damage through its ability to recognize and rapidly bind to DNA single or double strand breaks (D'Amours, et al., Biochem. J., 342, 249-268 (1999)).

The family of Poly (ADP-ribose) polymerases now includes around 18 proteins, that all display a certain level of homology in their catalytic domain but differ in their cellular functions (Ame et al., Bioessays., 26(8), 882-893 (2004)). Of this family PARP-1 (the founding member) and PARP-2 are so far the sole enzymes whose catalytic activity are stimulated by the occurrence of DNA strand breaks, making them unique in the family.

It is now known that PARP-1 participates in a variety of DNA-related functions including gene amplification, cell division, differentiation, apoptosis, DNA base excision repair as well as effects on telomere length and chromosome stability (d'Adda di Fagagna, et al., Nature Gen., 23(1), 76-80 (1999)).

Studies on the mechanism by which PARP-1 modulates DNA repair and other processes has identified its importance in the formation of poly (ADP-ribose) chains within the cellular nucleus (Althaus, F. R. and Richter, C., ADP-Ribosylation of Proteins: Enzymology and Biological Significance, Springer-Verlag, Berlin (1987)). The DNA-bound, activated PARP-1 utilizes NAD⁺ to synthesize poly (ADP-ribose) on a variety of nuclear target proteins, including topoisomerases, histones and PARP itself (Rhun, et al., Biochem. Biophys. Res. Commun., 245, 1-10 (1998))

Poly (ADP-ribosyl)ation has also been associated with malignant transformation. For example, PARP-1 activity is higher in the isolated nuclei of SV40-transformed fibroblasts, while both leukemic cells and colon cancer cells show higher enzyme activity than the equivalent normal leukocytes and colon mucosa (Miwa, et al., Arch. Biochem. Biophys., 181, 313-321 (1977); Burzio, et al., Proc. Soc. Exp. Bioi. Med., 149, 933-938 (1975); and Hirai, et al., Cancer Res., 43, 3441-3446 (1983)). More recently in malignant prostate tumours compared to begnine prostate cells significantly increased levels of active PARP (predominantly PARP-1) have been identified associated with higher levels of genetic instability (Mcnealy, et al., Anticancer Res., 23, 1473-1478 (2003))

A number of low-molecular-weight inhibitors of PARP-1 have been used to elucidate the functional role of poly (ADP-ribosyl)ation in DNA repair. In cells treated with alkylating agents, the inhibition of PARP leads to a marked increase in DNA-strand breakage and cell killing (Durkacz, et al., Nature, 283, 593-596 (1980); Berger, N. A., Radiation Research, 101, 4-14 (1985)).

Subsequently, such inhibitors have been shown to enhance the effects of radiation response by suppressing the repair of potentially lethal damage (Ben-Hur, et al., British Journal of Cancer, 49 (Suppl. VI), 34-42 (1984); Schlicker, et al., Int. J. Radiat. Bioi., 75, 91-100 (1999)). PARP inhibitors have been reported to be effective in radio sensitising hypoxic tumour cells (U.S. Pat. No. 5,032,617; U.S. Pat. No. 5,215,738 and U.S. Pat. No. 5,041,653). In certain tumour cell lines, chemical inhibition of PARP-1 (and PARP-2) activity is also associated with marked sensitisation to very low doses of radiation (Chalmers, Clin. Oncol., 16(1), 29-39 (2004))

Furthermore, PARP-1 knockout (PARP −/−) animals exhibit genomic instability in response to alkylating agents and γ-irradiation (Wang, et al., Genes Dev., 9, 509-520 (1995); Menissier de Murcia, et al., Proc. Natl. Acad. Sci. USA, 94, 7303-7307 (1997)). More recent data indicates that PARP-1 and PARP-2 possess both overlapping and non-redundant functions in the maintenance of genomic stability, making them both interesting targets (Menissier de Murcia, et al., EMBO. J., 22(9), 2255-2263 (2003)).

A role for PARP-1 has also been demonstrated in certain vascular diseases, septic shock, ischaemic injury and neurotoxicity (Cantoni, et al., Biochim. Biophys. Acta, 1014, 1-7 (1989); Szabo, et al., J. Clin. Invest., 100, 723-735 (1997)). Oxygen radical DNA damage that leads to strand breaks in DNA, which are subsequently recognised by PARP-1, is a major contributing factor to such disease states as shown by PARP-1 inhibitor studies (Cosi, et al., J. Neurosci. Res., 39, 38-46 (1994); Said, et al., Proc. Natl. Acad. Sci. U.S.A., 93, 4688-4692 (1996)). More recently, PARP has been demonstrated to play a role in the pathogenesis of haemorrhagic shock (Liaudet, et al., Proc. Natl. Acad. Sci. U.S.A., 97(3), 10203-10208 (2000)).

It has also been demonstrated that efficient retroviral infection of mammalian cells is blocked by the inhibition of PARP-1 activity. Such inhibition of recombinant retroviral vector infections was shown to occur in various different cell types (Gaken, et al., J. Virology, 70(6), 3992-4000 (1996)). Inhibitors of PARP-1 have thus been developed for the use in anti-viral therapies and in cancer treatment (WO 91/18591).

Moreover, PARP-1 inhibition has been speculated to delay the onset of aging characteristics in human fibroblasts (Rattan and Clark, Biochem. Biophys. Res. Comm., 201(2), 665-672 (1994)). This may be related to the role that PARP plays in controlling telomere function (d'Adda di Fagagna, et al., Nature Gen., 23(1), 76-80 (1999)).

PARP inhibitors are also thought to be relevant to the treatment of inflammatory bowel disease (Szabo C., Role of Poly(ADP-Ribose) Polymerase Activation in the Pathogenesis of Shock and Inflammation, In PARP as a Therapeutic Target; Ed J. Zhang, 2002 by CRC Press; 169-204), ulcerative colitis (Zingarelli, B, et al., Immunology, 113(4), 509-517 (2004)) and Crohn's disease (Jijon, H. B., et al., Am. J. Physiol. Gastrointest. Liver Physiol., 279, G641-G651 (2000).

Some of the present inventors have previously described (WO 02/36576) a class of 1(2H)-phthalazinone compounds which act as PARP inhibitors. The compounds have the general formula:

where A and B together represent an optionally substituted, fused aromatic ring and where R_(C) is represented by -L-R_(L). A large number of examples are of the formula:

where R represent one or more optional substituents.

Some of the present inventors described a particular class of the above compounds in WO 03/093261, which have the general formula as above, and wherein R is in the meta position, and the examples disclosed have the R group selected from:

The present inventors have now discovered that compounds with a different substituent groups to those above exhibit surprising levels of inhibition of the activity of PARP, and/or of potentiation of tumour cells to radiotherapy and various chemotherapies. In addition, the stability of the compounds of the present invention is in general improved over those compounds exemplified in WO 03/093261. Some of the compounds of the present invention also show good solubility in both aqueous media and phosphate buffer solution—enhanced solubility may be of use in formulation the compounds for administration by an IV route, or for oral formulations (e.g. liquid and small tablet forms) for pediatric use. The oral bioavailability of the compounds of the present invention may be enhanced.

Accordingly, the first aspect of the present invention provides a compound of the formula (I):

(including isomers, salts, solvates, chemically protected forms, and prodrugs thereof) wherein: A and B together represent an optionally substituted, fused aromatic ring; D is selected from: (i)

where Y¹ is selected from CH and N, Y² is selected from CH and N, Y³ is selected from CH, CF and N; and (ii)

where Q is O or S;

R^(D) is:

wherein R^(N1) is selected from H and optionally substituted C₁₋₁₀ alkyl; X is selected from a single bond, NR^(N2), CR^(C3)R^(C4) and C═O; R^(N2) is selected from H and optionally substituted C₁₋₁₀ alkyl; R^(C3) and R^(C4) are independently selected from H, R, C(═O)OR, where R is optionally substituted C₁₋₁₀ alkyl, optionally substituted C₅₋₂₀ aryl or optionally substituted C₃₋₂₀ heterocyclyl; Y is selected from NR^(N3) and CR^(C1)R^(C2). R^(C1) and R^(C2) are independently selected from H, R, C(═O)OR, where R is optionally substituted C₁₋₁₀ alkyl, optionally substituted C₅₋₂₀ aryl or optionally substituted C₃₋₂₀ heterocyclyl; R^(C1) and R^(C2) together with the carbon atom to which they are attached may form an optionally substituted spiro-fused C₅₋₇ carbocylic or heterocyclic ring; and when X is a single bond R^(N1) and R^(C2) may together with the N and C atoms to which they are bound, form an optionally substituted C₅₋₇ heterocylic ring; and when X is CR^(C3)R^(C4), R^(C2) and R^(C4) may together form an additional bond, such that there is a double bond between the atoms substituted by R^(C1) and R^(C3).

The possibilities for D are:

Formula Y¹ Y² Y³ Group

CH CH CH

CH CH CF

N CH CH

N CH CF

CH N CH

CH N CF

CH CH N

N N CH

N N CF

N CH N

CH N N

Q

O

S

A second aspect of the present invention provides a pharmaceutical composition comprising a compound of the first aspect and a pharmaceutically acceptable carrier or diluent.

A third aspect of the present invention provides the use of a compound of the first aspect in a method of treatment of the human or animal body.

A fourth aspect of the present invention provides the use of a compound as defined in the first aspect of the invention in the preparation of a medicament for:

(a) preventing poly(ADP-ribose) chain formation by inhibiting the activity of cellular PARP (PARP-1 and/or PARP-2); (b) the treatment of: vascular disease; septic shock; ischaemic injury, both cerebral and cardiovascular; reperfusion injury, both cerebral and cardiovascular; neurotoxicity, including acute and chronic treatments for stroke and Parkinsons disease; haemorraghic shock; inflammatory diseases, such as arthritis, inflammatory bowel disease, ulcerative colitis and Crohn's disease; multiple sclerosis; secondary effects of diabetes; as well as the acute treatment of cytoxicity following cardiovascular surgery or diseases ameliorated by the inhibition of the activity of PARP; (c) use as an adjunct in cancer therapy or for potentiating tumour cells for treatment with ionizing radiation or chemotherapeutic agents.

In particular, compounds as defined in the first aspect of the invention can be used in anti-cancer combination therapies (or as adjuncts) along with alkylating agents, such as methyl methanesulfonate (MMS), temozolomide and dacarbazine (DTIC), also with topoisomerase-1 inhibitors like Topotecan, Irinotecan, Rubitecan, Exatecan, Lurtotecan, Gimetecan, Diflomotecan (homocamptothecins); as well as 7-substituted non-silatecans; the 7-silyl camptothecins, BNP 1350; and non-camptothecin topoisomerase-I inhibitors such as indolocarbazoles also dual topoisomerase-I and II inhibitors like the benzophenazines, XR 11576/MLN 576 and benzopyridoindoles. Such combinations could be given, for example, as intravenous preparations or by oral administration as dependent on the preferred method of administration for the particular agent.

Other further aspects of the invention provide for the treatment of disease ameliorated by the inhibition of PARP, comprising administering to a subject in need of treatment a therapeutically-effective amount of a compound as defined in the first aspect, preferably in the form of a pharmaceutical composition and the treatment of cancer, comprising administering to a subject in need of treatment a therapeutically-effective amount of a compound as defined in the first aspect in combination, preferably in the form of a pharmaceutical composition, simultaneously or sequentially with radiotherapy (ionizing radiation) or chemotherapeutic agents.

In further aspects of the present invention, the compounds may be used in the preparation of a medicament for the treatment of cancer which is deficient in Homologous Recombination (HR) dependent DNA double strand break (DSB) repair activity, or in the treatment of a patient with a cancer which is deficient in HR dependent DNA DSB repair activity, comprising administering to said patient a therapeutically-effective amount of the compound.

The HR dependent DNA DSB repair pathway repairs double-strand breaks (DSBs) in DNA via homologous mechanisms to reform a continuous DNA helix (K. K. Khanna and S. P. Jackson, Nat. Genet. 27(3): 247-254 (2001)). The components of the HR dependent DNA DSB repair pathway include, but are not limited to, ATM (NM_(—)000051), RAD51 (NM_(—)002875), RAD51L1 (NM_(—)002877), RAD51C (NM_(—)002876), RAD51L3 (NM_(—)002878), DMC1 (NM_(—)007068), XRCC2 (NM_(—)005431), XRCC3 (NM_(—)005432), RAD52 (NM_(—)002879), RAD54L (NM_(—)003579), RAD54B (NM_(—)012415), BRCA1 (NM_(—)007295), BRCA2 (NM_(—)000059), RAD50 (NM_(—)005732), MRE11A (NM_(—)005590) and NBS1 (NM_(—)002485). Other proteins involved in the HR dependent DNA DSB repair pathway include regulatory factors such as EMSY (Hughes-Davies, et al., Cell, 115, pp 523-535). HR components are also described in Wood, et al., Science, 291, 1284-1289 (2001).

A cancer which is deficient in HR dependent DNA DSB repair may comprise or consist of one or more cancer cells which have a reduced or abrogated ability to repair DNA DSBs through that pathway, relative to normal cells i.e. the activity of the HR dependent DNA DSB repair pathway may be reduced or abolished in the one or more cancer cells.

The activity of one or more components of the HR dependent DNA DSB repair pathway may be abolished in the one or more cancer cells of an individual having a cancer which is deficient in HR dependent DNA DSB repair. Components of the HR dependent DNA DSB repair pathway are well characterised in the art (see for example, Wood, et al., Science, 291, 1284-1289 (2001)) and include the components listed above.

In some preferred embodiments, the cancer cells may have a BRCA1 and/or a BRCA2 deficient phenotype i.e. BRCA1 and/or BRCA2 activity is reduced or abolished in the cancer cells. Cancer cells with this phenotype may be deficient in BRCA1 and/or BRCA2, i.e. expression and/or activity of BRCA1 and/or BRCA2 may be reduced or abolished in the cancer cells, for example by means of mutation or polymorphism in the encoding nucleic acid, or by means of amplification, mutation or polymorphism in a gene encoding a regulatory factor, for example the EMSY gene which encodes a BRCA2 regulatory factor (Hughes-Davies, et al., Cell, 115, 523-535) or by an epigenetic mechanism such as gene promoter methylation.

BRCA1 and BRCA2 are known tumour suppressors whose wild-type alleles are frequently lost in tumours of heterozygous carriers (Jasin M., Oncogene, 21(58), 8981-93 (2002); Tutt, et al., Trends Mol. Med., 8(12), 571-6, (2002)). The association of BRCA1 and/or BRCA2 mutations with breast cancer is well-characterised in the art (Radice, P. J., Exp Clin Cancer Res., 21(3 Suppl), 9-12 (2002)). Amplification of the EMSY gene, which encodes a BRCA2 binding factor, is also known to be associated with breast and ovarian cancer.

Carriers of mutations in BRCA1 and/or BRCA2 are also at elevated risk of cancer of the ovary, prostate and pancreas.

In some preferred embodiments, the individual is heterozygous for one or more variations, such as mutations and polymorphisms, in BRCA1 and/or BRCA2 or a regulator thereof. The detection of variation in BRCA1 and BRCA2 is well-known in the art and is described, for example in EP 699 754, EP 705 903, Neuhausen, S. L. and Ostrander, E. A., Genet. Test, 1, 75-83 (1992); Janatova M., et al., Neoplasma, 50(4), 246-50 (2003). Determination of amplification of the BRCA2 binding factor EMSY is described in Hughes-Davies, et al., Cell, 115, 523-535).

Mutations and polymorphisms associated with cancer may be detected at the nucleic acid level by detecting the presence of a variant nucleic acid sequence or at the protein level by detecting the presence of a variant (i.e. a mutant or allelic variant) polypeptide.

DEFINITIONS

The term “aromatic ring” is used herein in the conventional sense to refer to a cyclic aromatic structure, that is, a cyclic structure having delocalised π-electron orbitals.

The aromatic ring fused to the main core, i.e. that formed by -A-B—, may bear further fused aromatic rings (resulting in, e.g. naphthyl or anthracenyl groups). The aromatic ring(s) may comprise solely carbon atoms, or may comprise carbon atoms and one or more heteroatoms, including but not limited to, nitrogen, oxygen, and sulfur atoms. The aromatic ring(s) preferably have five or six ring atoms.

The aromatic ring(s) may optionally be substituted. If a substituent itself comprises an aryl group, this aryl group is not considered to be a part of the aryl group to which it is attached. For example, the group biphenyl is considered herein to be a phenyl group (an aryl group comprising a single aromatic ring) substituted with a phenyl group. Similarly, the group benzylphenyl is considered to be a phenyl group (an aryl group comprising a single aromatic ring) substituted with a benzyl group.

In one group of preferred embodiments, the aromatic group comprises a single aromatic ring, which has five or six ring atoms, which ring atoms are selected from carbon, nitrogen, oxygen, and sulfur, and which ring is optionally substituted. Examples of these groups include, but are not limited to, benzene, pyrazine, pyrrole, thiazole, isoxazole, and oxazole. 2-Pyrone can also be considered to be an aromatic ring, but is less preferred.

If the aromatic ring has six atoms, then preferably at least four, or even five or all, of the ring atoms are carbon. The other ring atoms are selected from nitrogen, oxygen and sulphur, with nitrogen and oxygen being preferred. Suitable groups include a ring with: no hetero atoms (benzene); one nitrogen ring atom (pyridine); two nitrogen ring atoms (pyrazine, pyrimidine and pyridazine); one oxygen ring atom (pyrone); and one oxygen and one nitrogen ring atom (oxazine).

If the aromatic ring has five ring atoms, then preferably at least three of the ring atoms are carbon. The remaining ring atoms are selected from nitrogen, oxygen and sulphur. Suitable rings include a ring with: one nitrogen ring atom (pyrrole); two nitrogen ring atoms (imidazole, pyrazole); one oxygen ring atom (furan); one sulphur ring atom (thiophene); one nitrogen and one sulphur ring atom (isothiazole, thiazole); and one nitrogen and one oxygen ring atom (isoxazole or oxazole).

The aromatic ring may bear one or more substituent groups at any available ring position. These substituents are selected from halo, nitro, hydroxy, ether, thiol, thioether, amino, C₁₋₇ alkyl, C₃₋₂₀ heterocyclyl and C₅₋₂₀ aryl. The aromatic ring may also bear one or more substituent groups which together form a ring. In particular these may be of formula —(CH₂)_(m)— or —O—(CH₂)_(p)—O—, where m is 2, 3, 4 or 5 and p is 1, 2 or 3.

Spiro-fused rings: The term “spiro-fused rings” as used herein pertains to a carbocyclic or heterocyclic ring which is fused to the remainder of the molecule at a single carbon atom. The ring itself may contain only carbon ring atoms, and hence be a carbocyclic ring, or may contain one or more heteroatoms and thus be a heterocyclic ring. Examples of C₅₋₇ carbocyclic and heterocyclic rings are given herein.

Nitrogen-containing C₅₋₇ heterocyclylic ring: The term “nitrogen-containing C₅₋₇ heterocyclylic ring” as used herein, pertains to a C₅₋₇ heterocyclylic ring, as defined below with relation to heterocyclyl, having at least one nitrogen ring atom.

Alkyl: The term “alkyl” as used herein, pertains to a monovalent moiety obtained by removing a hydrogen atom from a carbon atom of a hydrocarbon compound having from 1 to 20 carbon atoms (unless otherwise specified), which may be aliphatic or alicyclic, and which may be saturated or unsaturated (e.g. partially unsaturated, fully unsaturated). Thus, the term “alkyl” includes the sub-classes alkenyl, alkynyl, cycloalkyl, cycloalkyenyl, cylcoalkynyl, etc., discussed below.

In the context of alkyl groups, the prefixes (e.g. C₁₋₄, C₁₋₇, C₁₋₂₀, C₂₋₇, C₃₋₇, etc.) denote the number of carbon atoms, or range of number of carbon atoms. For example, the term “C₁₋₄ alkyl”, as used herein, pertains to an alkyl group having from 1 to 4 carbon atoms. Examples of groups of alkyl groups include C₁₋₄ alkyl (“lower alkyl”), C₁₋₇ alkyl, and C₁₋₂₀ alkyl. Note that the first prefix may vary according to other limitations; for example, for unsaturated alkyl groups, the first prefix must be at least 2; for cyclic alkyl groups, the first prefix must be at least 3; etc.

Examples of (unsubstituted) saturated alkyl groups include, but are not limited to, methyl (C₁), ethyl (C₂), propyl (C₃), butyl (C₄), pentyl (C₅), hexyl (C₆), heptyl (C₇), octyl (C₈), nonyl (C₉), decyl (C₁₀), undecyl (C₁₁), dodecyl (C₁₂), tridecyl (C₁₃), tetradecyl (C₁₄), pentadecyl (C₁₅), and eicodecyl (C₂₀).

Examples of (unsubstituted) saturated linear alkyl groups include, but are not limited to, methyl (C₁), ethyl (C₂), n-propyl (C₃), n-butyl (C₄), n-pentyl (amyl) (C₅), n-hexyl (C₆), and n-heptyl (C₇).

Examples of (unsubstituted) saturated branched alkyl groups include, but are not limited to, iso-propyl (C₃), iso-butyl (C₄), sec-butyl (C₄), tert-butyl (C₄), iso-pentyl (C₅), and neo-pentyl (C₅).

Alkenyl: The term “alkenyl”, as used herein, pertains to an alkyl group having one or more carbon-carbon double bonds. Examples of alkenyl groups include C₂₋₄ alkenyl, C₂₋₇ alkenyl, C₂₋₂₀ alkenyl.

Examples of (unsubstituted) unsaturated alkenyl groups include, but are not limited to, ethenyl(vinyl, —CH≡CH₂), 1-propenyl (—CH═CH—CH₃), 2-propenyl(allyl, —CH—CH═CH₂), isopropenyl (1-methylvinyl, —C(CH₃)═CH₂), butenyl (C₄), pentenyl (C₅), and hexenyl (C₆).

Alkynyl: The term “alkynyl”, as used herein, pertains to an alkyl group having one or more carbon-carbon triple bonds. Examples of alkynyl groups include C₂₋₄ alkynyl, C₂₋₇ alkynyl, C₂₋₂₀ alkynyl.

Examples of (unsubstituted) unsaturated alkynyl groups include, but are not limited to, ethynyl(ethinyl, —C≡CH) and 2-propynyl(propargyl, —CH₂—C≡CH).

Cycloalkyl: The term “cycloalkyl”, as used herein, pertains to an alkyl group which is also a cyclyl group; that is, a monovalent moiety obtained by removing a hydrogen atom from an alicyclic ring atom of a carbocyclic ring of a carbocyclic compound, which carbocyclic ring may be saturated or unsaturated (e.g. partially unsaturated, fully unsaturated), which moiety has from 3 to 20 carbon atoms (unless otherwise specified), including from 3 to 20 ring atoms. Thus, the term “cycloalkyl” includes the sub-classes cycloalkenyl and cycloalkynyl. Preferably, each ring has from 3 to 7 ring atoms. Examples of groups of cycloalkyl groups include C₃₋₂₀ cycloalkyl, C₃₋₁₅ cycloalkyl, C₃₋₁₀ cycloalkyl, C₃₋₇ cycloalkyl.

Examples of cycloalkyl groups include, but are not limited to, those derived from:

-   -   saturated monocyclic hydrocarbon compounds:         cyclopropane (C₃), cyclobutane (C₄), cyclopentane (C₅),         cyclohexane (C₆), cycloheptane (C₇), methylcyclopropane (C₄),         dimethylcyclopropane (C₅), methylcyclobutane (C₅),         dimethylcyclobutane (C₆), methylcyclopentane (C₆),         dimethylcyclopentane (C₇), methylcyclohexane (C₇),         dimethylcyclohexane (C₈), menthane (C₁₀);     -   unsaturated monocyclic hydrocarbon compounds:         cyclopropene (C₃), cyclobutene (C₄), cyclopentene (C₅),         cyclohexene (C₆), methylcyclopropene (C₄), dimethylcyclopropene         (C₅), methylcyclobutene (C₅), dimethylcyclobutene (C₆),         methylcyclopentene (C₆), dimethylcyclopentene (C₇),         methylcyclohexene (C₇), dimethylcyclohexene (C₈);     -   saturated polycyclic hydrocarbon compounds:         thujane (C₁₀), carane (C₁₀), pinane (C₁₀), bornane (C₁₀),         norcarane (C₇), norpinane (C₇), norbornane (C₇), adamantane         (C₁₀), decalin (decahydronaphthalene) (C₁₀);     -   unsaturated polycyclic hydrocarbon compounds:         camphene (C₁₀), limonene (C₁₀), pinene (C₁₀);     -   polycyclic hydrocarbon compounds having an aromatic ring:         indene (C₉), indane (e.g., 2,3-dihydro-1H-indene) (C₉),         tetraline (1,2,3,4-tetrahydronaphthalene) (C₁₀), acenaphthene         (C₁₂), fluorene (C₁₃), phenalene (C₁₃), acephenanthrene (C₁₅),         aceanthrene (C₁₆), cholanthrene (C₂₀).

Heterocyclyl: The term “heterocyclyl”, as used herein, pertains to a monovalent moiety obtained by removing a hydrogen atom from a ring atom of a heterocyclic compound, which moiety has from 3 to 20 ring atoms (unless otherwise specified), of which from 1 to 10 are ring heteroatoms. Preferably, each ring has from 3 to 7 ring atoms, of which from 1 to 4 are ring heteroatoms.

In this context, the prefixes (e.g. C₃₋₂₀, C₃₋₇, C₅₋₆, etc.) denote the number of ring atoms, or range of number of ring atoms, whether carbon atoms or heteroatoms. For example, the term “C₅₋₆heterocyclyl”, as used herein, pertains to a heterocyclyl group having 5 or 6 ring atoms. Examples of groups of heterocyclyl groups include C₃₋₂₀ heterocyclyl, C₅₋₂₀ heterocyclyl, C₃₋₁₅ heterocyclyl, C₅₋₁₅ heterocyclyl, C₃₋₁₂ heterocyclyl, C₅₋₁₂ heterocyclyl, C₃₋₁₀ heterocyclyl, C₅₋₁₀ heterocyclyl, C₃₋₇ heterocyclyl, C₅₋₇ heterocyclyl, and C₅₋₆ heterocyclyl.

Examples of monocyclic heterocyclyl groups include, but are not limited to, those derived from:

N₁: aziridine (C₃), azetidine (C₄), pyrrolidine (tetrahydropyrrole) (C₅), pyrroline (e.g., 3-pyrroline, 2,5-dihydropyrrole) (C₅), 2H-pyrrole or 3H-pyrrole (isopyrrole, isoazole) (C₅), piperidine (C₆), dihydropyridine (C₆), tetrahydropyridine (C₆), azepine (C₇); O₁: oxirane (C₃), oxetane (C₄), oxolane (tetrahydrofuran) (C₅), oxole (dihydrofuran) (C₅), oxane (tetrahydropyran) (C₆), dihydropyran (C₆), pyran (C₆), oxepin (C₇); S₁: thiirane (C₃), thietane (C₄), thiolane (tetrahydrothiophene) (C₅), thiane (tetrahydrothiopyran) (C₆), thiepane (C₇); O₂: dioxolane (C₅), dioxane (C₆), and dioxepane (C₇); O₃: trioxane (C₆); N₂: imidazolidine (C₅), pyrazolidine (diazolidine) (C₅), imidazoline (C₅), pyrazoline (dihydropyrazole) (C₅), piperazine (C₆); N₁O₁: tetrahydrooxazole (C₅), dihydrooxazole (C₅), tetrahydroisoxazole (C₅), dihydroisoxazole (C₅), morpholine (C₆), tetrahydrooxazine (C₆), dihydrooxazine (C₆), oxazine (C₆); N₁S₁: thiazoline (C₅), thiazolidine (C₅), thiomorpholine (C₆); N₂O₁: oxadiazine (C₆); O₁S₁: oxathiole (C₅) and oxathiane (thioxane) (C₆); and, N₁O₁S₁: oxathiazine (C₆).

Examples of substituted (non-aromatic) monocyclic heterocyclyl groups include those derived from saccharides, in cyclic form, for example, furanoses (C₅), such as arabinofuranose, lyxofuranose, ribofuranose, and xylofuranse, and pyranoses (C₆), such as allopyranose, altropyranose, glucopyranose, mannopyranose, gulopyranose, idopyranose, galactopyranose, and talopyranose.

Spiro-C₃₋₇ cycloalkyl or heterocyclyl: The term “spiro C₃₋₇ cycloalkyl or heterocyclyl” as used herein, refers to a C₃₋₇ cycloalkyl or C₃₋₇ heterocyclyl ring joined to another ring by a single atom common to both rings.

C₅₋₂₀ aryl: The term “C₅₋₂₀ aryl” as used herein, pertains to a monovalent moiety obtained by removing a hydrogen atom from an aromatic ring atom of a C₅₋₂₀ aromatic compound, said compound having one ring, or two or more rings (e.g., fused), and having from 5 to 20 ring atoms, and wherein at least one of said ring(s) is an aromatic ring. Preferably, each ring has from 5 to 7 ring atoms.

The ring atoms may be all carbon atoms, as in “carboaryl groups” in which case the group may conveniently be referred to as a “C₅₋₂₀ carboaryl” group.

Examples of C₅₋₂₀ aryl groups which do not have ring heteroatoms (i.e. C₅₋₂₀ carboaryl groups) include, but are not limited to, those derived from benzene (i.e. phenyl) (C₆), naphthalene (C₁₀), anthracene (C₁₄), phenanthrene (C₁₄), and pyrene (C₁₆).

Alternatively, the ring atoms may include one or more heteroatoms, including but not limited to oxygen, nitrogen, and sulfur, as in “heteroaryl groups”. In this case, the group may conveniently be referred to as a “C₅₋₂₀ heteroaryl” group, wherein “C₅₋₂₀” denotes ring atoms, whether carbon atoms or heteroatoms. Preferably, each ring has from 5 to 7 ring atoms, of which from 0 to 4 are ring heteroatoms.

Examples of C₅₋₂₀ heteroaryl groups include, but are not limited to, C₅ heteroaryl groups derived from furan (oxole), thiophene (thiole), pyrrole (azole), imidazole (1,3-diazole), pyrazole (1,2-diazole), triazole, oxazole, isoxazole, thiazole, isothiazole, oxadiazole, tetrazole and oxatriazole; and C₆ heteroaryl groups derived from isoxazine, pyridine (azine), pyridazine (1,2-diazine), pyrimidine (1,3-diazine; e.g., cytosine, thymine, uracil), pyrazine (1,4-diazine) and triazine.

The heteroaryl group may be bonded via a carbon or hetero ring atom.

Examples of C₅₋₂₀ heteroaryl groups which comprise fused rings, include, but are not limited to, C₉ heteroaryl groups derived from benzofuran, isobenzofuran, benzothiophene, indole, isoindole; C₁₀ heteroaryl groups derived from quinoline, isoquinoline, benzodiazine, pyridopyridine; C₁₄ heteroaryl groups derived from acridine and xanthene.

The above alkyl, heterocyclyl, and aryl groups, whether alone or part of another substituent, may themselves optionally be substituted with one or more groups selected from themselves and the additional substituents listed below.

Halo: —F, —Cl, —Br, and —I. Hydroxy: —OH.

Ether: —OR, wherein R is an ether substituent, for example, a C₁₋₇ alkyl group (also referred to as a C₁₋₇ alkoxy group), a C₃₋₂₀ heterocyclyl group (also referred to as a C₃₋₂₀ heterocyclyloxy group), or a C₅₋₂₀ aryl group (also referred to as a C₅₋₂₀ aryloxy group), preferably a C₁₋₇ alkyl group.

Nitro: —NO₂.

Cyano (nitrile, carbonitrile): —CN. Acyl (keto): —C(═O)R, wherein R is an acyl substituent, for example, H, a C₁₋₇ alkyl group (also referred to as C₁₋₇ alkylacyl or C₁₋₇ alkanoyl), a C₃₋₂₀ heterocyclyl group (also referred to as C₃₋₂₀ heterocyclylacyl), or a C₅₋₂₀ aryl group (also referred to as C₅₋₂₀ arylacyl), preferably a C₁₋₇ alkyl group. Examples of acyl groups include, but are not limited to, —C(═O)CH₃ (acetyl), —C(═O)CH₂CH₃ (propionyl), —C(═O)C(CH₃)₃ (butyryl), and —C(═O)Ph (benzoyl, phenone). Carboxy(carboxylic acid): —COOH. Ester (carboxylate, carboxylic acid ester, oxycarbonyl): —C(═O)OR, wherein R is an ester substituent, for example, a C₁₋₇ alkyl group, a C₃₋₂₀ heterocyclyl group, or a C₅₋₂₀ aryl group, preferably a C₁₋₇ alkyl group. Examples of ester groups include, but are not limited to, —C(═O)OCH₃, —C(═O)OCH₂CH₃, —C(═O)OC(CH₃)₃, and —C(═O)OPh. Amido (carbamoyl, carbamyl, aminocarbonyl, carboxamide): —C(═O)NR¹R², wherein R¹ and R² are independently amino substituents, as defined for amino groups. Examples of amido groups include, but are not limited to, —C(═O)NH₂, —C(═O)NHCH₃, —C(═O)N(CH₃)₂, —C(═O)NHCH₂CH₃, and —C(═O)N(CH₂CH₃)₂, as well as amido groups in which R¹ and R², together with the nitrogen atom to which they are attached, form a heterocyclic structure as in, for example, piperidinocarbonyl, morpholinocarbonyl, thiomorpholinocarbonyl, and piperazinylcarbonyl. Amino: —NR¹R², wherein R¹ and R² are independently amino substituents, for example, hydrogen, a C₁₋₇ alkyl group (also referred to as C₁₋₇ alkylamino or di-C₁₋₇ alkylamino), a C₃₋₂₀ heterocyclyl group, or a C₅₋₂₀ aryl group, preferably H or a C₁₋₇ alkyl group, or, in the case of a “cyclic” amino group, R¹ and R², taken together with the nitrogen atom to which they are attached, form a heterocyclic ring having from 4 to 8 ring atoms. Examples of amino groups include, but are not limited to, —NH₂, —NHCH₃, —NHCH(CH₃)₂, —N(CH₃)₂, —N(CH₂CH₃)₂, and —NHPh. Examples of cyclic amino groups include, but are not limited to, aziridinyl, azetidinyl, pyrrolidinyl, piperidino, piperazinyl, perhydrodiazepinyl, morpholino, and thiomorpholino. In particular, the cyclic amino groups may be substituted on their ring by any of the substituents defined here, for example carboxy, carboxylate and amido. Acylamido(acylamino): —NR¹C(═O)R², wherein R¹ is an amide substituent, for example, hydrogen, a C₁₋₇ alkyl group, a C₃₋₂₀ heterocyclyl group, or a C₅₋₂₀ aryl group, preferably H or a C₁₋₇ alkyl group, most preferably H, and R² is an acyl substituent, for example, a C₁₋₇ alkyl group, a C₃₋₂₀ heterocyclyl group, or a C₅₋₂₀ aryl group, preferably a C₁₋₇ alkyl group. Examples of acylamide groups include, but are not limited to, —NHC(═O)CH₃, —NHC(═O)CH₂CH₃, and —NHC(═O)Ph. R¹ and R² may together form a cyclic structure, as in, for example, succinimidyl, maleimidyl, and phthalimidyl:

Ureido: —N(R¹)CONR²R³ wherein R² and R³ are independently amino substituents, as defined for amino groups, and R¹ is a ureido substituent, for example, hydrogen, a C₁₋₇alkyl group, a C₃₋₂₀heterocyclyl group, or a C₅₋₂₀aryl group, preferably hydrogen or a C₁₋₇alkyl group. Examples of ureido groups include, but are not limited to, —NHCONH₂, —NHCONHMe, —NHCONHEt, —NHCONMe₂, —NHCONEt₂, —NMeCONH₂, —NMeCONHMe, —NMeCONHEt, —NMeCONMe₂, —NMeCONEt₂ and —NHCONHPh. Acyloxy (reverse ester): —OC(═O)R, wherein R is an acyloxy substituent, for example, a C₁₋₇ alkyl group, a C₃₋₂₀ heterocyclyl group, or a C₅₋₂₀ aryl group, preferably a C₁₋₇ alkyl group. Examples of acyloxy groups include, but are not limited to, —OC(═O)CH₃ (acetoxy), —OC(═O)CH₂CH₃, —OC(═O)C(CH₃)₃, —OC(═O)Ph, —OC(═O)C₆H₄F, and —OC(═O)CH₂Ph.

Thiol: —SH.

Thioether (sulfide): —SR, wherein R is a thioether substituent, for example, a C₁₋₇ alkyl group (also referred to as a C₁₋₇ alkylthio group), a C₃₋₂₀ heterocyclyl group, or a C₅₋₂₀ aryl group, preferably a C₁₋₇ alkyl group. Examples of C₁₋₇ alkylthio groups include, but are not limited to, —SCH₃ and —SCH₂CH₃. Sulfoxide (sulfinyl): —S(═O)R, wherein R is a sulfoxide substituent, for example, a C₁₋₇ alkyl group, a C₃₋₂₀ heterocyclyl group, or a C₅₋₂₀ aryl group, preferably a C₁₋₇ alkyl group. Examples of sulfoxide groups include, but are not limited to, —S(═O)CH₃ and —S(═O)CH₂CH₃. Sulfonyl (sulfone): —S(═O)₂R, wherein R is a sulfone substituent, for example, a C₁₋₇ alkyl group, a C₃₋₂₀ heterocyclyl group, or a C₅₋₂₀ aryl group, preferably a C₁₋₇ alkyl group. Examples of sulfone groups include, but are not limited to, —S(═O)₂CH₃ (methanesulfonyl, mesyl), —S(═O)₂CF₃, —S(═O)₂CH₂CH₃, and 4-methylphenylsulfonyl(tosyl). Thioamido(thiocarbamyl): —C(═S)NR¹R², wherein R¹ and R² are independently amino substituents, as defined for amino groups. Examples of amido groups include, but are not limited to, —C(═S)NH₂, —C(═S)NHCH₃, —C(═S)N(CH₃)₂, and —C(═S)NHCH₂CH₃. Sulfonamino: —NR¹S(═O)₂R, wherein R¹ is an amino substituent, as defined for amino groups, and R is a sulfonamino substituent, for example, a C₁₋₇alkyl group, a C₃₋₂₀heterocyclyl group, or a C₅₋₂₀aryl group, preferably a C₁₋₇alkyl group. Examples of sulfonamino groups include, but are not limited to, —NHS(═O)₂CH₃, —NHS(═O)₂Ph and —N(CH₃)S(═O)₂C₆H₅.

As mentioned above, the groups that form the above listed substituent groups, e.g. C₁₋₇ alkyl, C₃₋₂₀ heterocyclyl and C₅₋₂₀ aryl, may themselves be substituted. Thus, the above definitions cover substituent groups which are substituted.

Further Preferences

The following preferences can apply to each aspect of the present invention, where applicable.

In the present invention, the fused aromatic ring(s) represented by -A-B— preferably consist of solely carbon ring atoms, and thus may be benzene, naphthalene, and is more preferably benzene. As described above, these rings may be substituted, but in some embodiments are preferably unsubstituted.

If the fused aromatic ring represented by -A-B— bears a substituent group, it is preferably attached to the atom which itself is attached to the central ring β- to the carbon atom in the central ring. Thus, if the fused aromatic ring is a benzene ring, the preferred place of substitution is shown in the formula below by *:

which is usually termed the 5-position of the phthalazinone moiety.

The substituent is preferably an alkoxy, amino, halo or hydroxy group, and more preferably a C₁₋₇ alkoxy group (e.g. —OMe).

If the substituent is a halo, it may also be at the 6-, 7-, or 8-position of the phthalazinone moiety, but is preferably at the 8-position. The halo is preferably chloro or fluoro and more preferably fluoro.

Preferably, D is selected from phenylene, fluoro-phenylene, pyridylene, fluoro-pyrdiylene, furanylene and thiophenylene.

More preferably D is selected from:

Most preferably D is selected from:

Most preferably D is:

Preferably X is selected from a single bond, NR^(N2) and CR^(C3)R^(C4) and Y is CR^(C1)R^(C2).

In some embodiments, X is NR^(N2). In these embodiments, R^(C1) and R^(C2) are preferably H and it is further preferred that R^(N2) is H. In other embodiments, X is CR^(C3)R^(C4). In these embodiments, R^(C1) and R^(C2) are preferably H and it is further preferred that R^(C3) and R^(C4) are H.

In some embodiments, X is preferably a single bond, such that R^(D) is a five-membered ring. In these compounds it may be preferred that at least one of R^(N1), R^(C1) and R^(C2) is not hydrogen. In some of these preferred compounds, only one of R^(N1), R^(C1) and R^(C2) is not hydrogen. In others of these preferred compounds, two or three of R^(N1), R^(C1) and R^(C2) is not hydrogen.

Preferred groups for R^(C1) or R^(C2) include, but are not limited to, C₁₋₄ alkyl, which are preferably unsubstituted, e.g. methyl, ethyl, propyl, with methyl being preferred in some compounds.

When R^(N1) is not hydrogen, R^(C1) may be preferably methyl, with R^(C2) being preferably selected from H and methyl, more preferably methyl.

When R^(N1) is hydrogen, it may be preferred that R^(C2) is also hydrogen, and that R^(C1) is C₁₋₄ alkyl (e.g. methyl), preferably substituted at its terminus with a carboxy or amido group. The amino substituents of the amido group, together with the N atom to which they are attached, are preferably cyclic. The cyclic part of the amido group is preferably a C₅₋₇ nitrogen containing heterocyclic group, for example, pyrrolindinyl, piperazinyl, homopiperazinyl, piperidinyl, morpholino, all of which may be further substituted, as described above. In particular, substituent groups may include, but are not limited to, hydroxyl, substituted and unsubstituted C₁₋₄ alkyl (e.g. methyl, hydroxymethyl, methoxy-ethyl, dimethylamino-ethyl) and C₅₋₇ heterocyclyl (e.g. N-piperidinyl, morpholino).

Preferred groups for R^(N1) include, but are not limited to, C₁₋₄ alkyl (e.g. methyl), preferably substituted at its terminus with a carboxy or amido group, and additionally an ester group. The amino substituents of the amido group, together with the N atom to which they are attached. are preferably cyclic. The cyclic part of the amido group is preferably a C₅₋₇ nitrogen containing heterocyclic group, for example, pyrrolindinyl, piperazinyl, homopiperazinyl, piperidinyl, morpholino, all of which may be further substituted, as described above. In particular, substituent groups may include, but are not limited to, hydroxyl, substituted and unsubstituted C₁₋₄ alkyl (e.g. methyl, hydroxymethyl, hydroxyethyl, methoxy-ethyl, dimethylamino-ethyl) and C₅₋₇ heterocyclyl (e.g. N-piperidinyl, morpholino). Where appropriate, the above preferences may be taken in combination with each other.

In some embodiments, Y is NR^(N3), and these embodiments X is preferably C═O. In these embodiments, R^(N1) and R^(N2) are preferably selected from H, and C₁₋₄ alkyl, and are both more preferably H.

Includes Other Forms

Included in the above are the well known ionic, salt, solvate, and protected forms of these substituents. For example, a reference to carboxylic acid (—COOH) also includes the anionic (carboxylate) form (—COO⁻), a salt or solvate thereof, as well as conventional protected forms. Similarly, a reference to an amino group includes the protonated form (—N⁺HR¹R²), a salt or solvate of the amino group, for example, a hydrochloride salt, as well as conventional protected forms of an amino group. Similarly, a reference to a hydroxyl group also includes the anionic form (—O⁻), a salt or solvate thereof, as well as conventional protected forms of a hydroxyl group.

Isomers, Salts, Solvates, Protected Forms, and Prodrugs

Certain compounds may exist in one or more particular geometric, optical, enantiomeric, diasterioisomeric, epimeric, stereoisomeric, tautomeric, conformational, or anomeric forms, including but not limited to, cis- and trans-forms; E- and Z-forms; c-, t-, and r-forms; endo- and exo-forms; R-, S-, and meso-forms; D- and L-forms; d- and l-forms; (+) and (−) forms; keto-, enol-, and enolate-forms; syn- and anti-forms; synclinal- and anticlinal-forms; α- and β-forms; axial and equatorial forms; boat-, chair-, twist-, envelope-, and halfchair-forms; and combinations thereof, hereinafter collectively referred to as “isomers” (or “isomeric forms”).

If the compound is in crystalline form, it may exist in a number of different polymorphic forms.

Note that, except as discussed below for tautomeric forms, specifically excluded from the term “isomers”, as used herein, are structural (or constitutional) isomers (i.e. isomers which differ in the connections between atoms rather than merely by the position of atoms in space). For example, a reference to a methoxy group, —OCH₃, is not to be construed as a reference to its structural isomer, a hydroxymethyl group, —CH₂OH. Similarly, a reference to ortho-chlorophenyl is not to be construed as a reference to its structural isomer, meta-chlorophenyl. However, a reference to a class of structures may well include structurally isomeric forms falling within that class (e.g., C₁₋₇ alkyl includes n-propyl and iso-propyl; butyl includes n-, iso-, sec-, and tert-butyl; methoxyphenyl includes ortho-, meta-, and para-methoxyphenyl).

The above exclusion does not pertain to tautomeric forms, for example, keto-, enol-, and enolate-forms, as in, for example, the following tautomeric pairs: keto/enol, imine/enamine, amide/imino alcohol, amidine/amidine, nitroso/oxime, thioketone/enethiol, N-nitroso/hyroxyazo, and nitro/aci-nitro.

Particularly relevant to the present invention is the tautomeric pair illustrated below:

Note that specifically included in the term “isomer” are compounds with one or more isotopic substitutions. For example, H may be in any isotopic form, including ¹H, ²H (D), and ³H (T); C may be in any isotopic form, including ¹²C, ¹³C, and ¹⁴C; O may be in any isotopic form, including ¹⁶O and ¹⁸O; and the like.

Unless otherwise specified, a reference to a particular compound includes all such isomeric forms, including (wholly or partially) racemic and other mixtures thereof. Methods for the preparation (e.g. asymmetric synthesis) and separation (e.g. fractional crystallisation and chromatographic means) of such isomeric forms are either known in the art or are readily obtained by adapting the methods taught herein, or known methods, in a known manner.

Unless otherwise specified, a reference to a particular compound also includes ionic, salt, solvate, and protected forms of thereof, for example, as discussed below, as well as its different polymorphic forms.

It may be convenient or desirable to prepare, purify, and/or handle a corresponding salt of the active compound, for example, a pharmaceutically-acceptable salt. Examples of pharmaceutically acceptable salts are discussed in Berge, et al., “Pharmaceutically Acceptable Salts”, J. Pharm. Sci., 66, 1-19 (1977).

For example, if the compound is anionic, or has a functional group which may be anionic (e.g., —COOH may be —COO⁻), then a salt may be formed with a suitable cation. Examples of suitable inorganic cations include, but are not limited to, alkali metal ions such as Na⁺ and K⁺, alkaline earth cations such as Ca²⁺ and Mg²⁺, and other cations such as Al³⁺. Examples of suitable organic cations include, but are not limited to, ammonium ion (i.e., NH₄ ⁺) and substituted ammonium ions (e.g., NH₃R⁺, NH₂R₂ ⁺, NHR₃ ⁺, NR₄ ⁺). Examples of some suitable substituted ammonium ions are those derived from: ethylamine, diethylamine, dicyclohexylamine, triethylamine, butylamine, ethylenediamine, ethanolamine, diethanolamine, piperazine, benzylamine, phenylbenzylamine, choline, meglumine, and tromethamine, as well as amino acids, such as lysine and arginine. An example of a common quaternary ammonium ion is N(CH₃)₄ ⁺.

If the compound is cationic, or has a functional group which may be cationic (e.g., —NH₂ may be —NH₃ ⁺), then a salt may be formed with a suitable anion. Examples of suitable inorganic anions include, but are not limited to, those derived from the following inorganic acids: hydrochloric, hydrobromic, hydroiodic, sulfuric, sulfurous, nitric, nitrous, phosphoric, and phosphorous. Examples of suitable organic anions include, but are not limited to, those derived from the following organic acids: acetic, propionic, succinic, gycolic, stearic, palmitic, lactic, malic, pamoic, tartaric, citric, gluconic, ascorbic, maleic, hydroxymaleic, phenylacetic, glutamic, aspartic, benzoic, cinnamic, pyruvic, salicyclic, sulfanilic, 2-acetyoxybenzoic, fumaric, toluenesulfonic, methanesulfonic, ethanesulfonic, ethane disulfonic, oxalic, isethionic, valeric, and gluconic. Examples of suitable polymeric anions include, but are not limited to, those derived from the following polymeric acids: tannic acid, carboxymethyl cellulose.

It may be convenient or desirable to prepare, purify, and/or handle a corresponding solvate of the active compound. The term “solvate” is used herein in the conventional sense to refer to a complex of solute (e.g. active compound, salt of active compound) and solvent. If the solvent is water, the solvate may be conveniently referred to as a hydrate, for example, a mono-hydrate, a di-hydrate, a tri-hydrate, etc.

It may be convenient or desirable to prepare, purify, and/or handle the active compound in a chemically protected form. The term “chemically protected form,” as used herein, pertains to a compound in which one or more reactive functional groups are protected from undesirable chemical reactions, that is, are in the form of a protected or protecting group (also known as a masked or masking group or a blocked or blocking group). By protecting a reactive functional group, reactions involving other unprotected reactive functional groups can be performed, without affecting the protected group; the protecting group may be removed, usually in a subsequent step, without substantially affecting the remainder of the molecule. See, for example, “Protective Groups in Organic Synthesis” (T. Green and P. Wuts; 3rd Edition; John Wiley and Sons, 1999).

For example, a hydroxy group may be protected as an ether (—OR) or an ester (—OC(═O)R), for example, as: a t-butyl ether; a benzyl, benzhydryl(diphenylmethyl), or trityl (triphenylmethyl)ether; a trimethylsilyl or t-butyldimethylsilyl ether; or an acetyl ester (—OC(═O)CH₃, —OAc).

For example, an aldehyde or ketone group may be protected as an acetal or ketal, respectively, in which the carbonyl group (>C═O) is converted to a diether (>C(OR)₂), by reaction with, for example, a primary alcohol. The aldehyde or ketone group is readily regenerated by hydrolysis using a large excess of water in the presence of acid.

For example, an amine group may be protected, for example, as an amide or a urethane, for example, as: a methyl amide (—NHCO—CH₃); a benzyloxy amide (—NHCO—OCH₂C₆H₅, —NH-Cbz); as a t-butoxy amide (—NHCO—OC(CH₃)₃, —NH-Boc); a 2-biphenyl-2-propoxy amide (—NHCO—OC(CH₃)₂C₆H₄C₆H₅, —NH-Bpoc), as a 9-fluorenylmethoxy amide (—NH-Fmoc), as a 6-nitroveratryloxy amide (—NH-Nvoc), as a 2-trimethylsilylethyloxy amide (—NH-Teoc), as a 2,2,2-trichloroethyloxy amide (—NH-Troc), as an allyloxy amide (—NH-Alloc), as a 2(-phenylsulphonyl)ethyloxy amide (—NH-Psec); or, in suitable cases, as an N-oxide (>NO•u −).

For example, a carboxylic acid group may be protected as an ester for example, as: a C₁₋₇ alkyl ester (e.g. a methyl ester; a t-butyl ester); a C₁₋₇ haloalkyl ester (e.g. a C₁₇ trihaloalkyl ester); a triC₁₋₇ alkylsilyl-C₁₋₇ alkyl ester; or a C₅₋₂₀ aryl-C₁₋₇ alkyl ester (e.g. a benzyl ester; a nitrobenzyl ester); or as an amide, for example, as a methyl amide.

For example, a thiol group may be protected as a thioether (—SR), for example, as: a benzyl thioether; an acetamidomethyl ether (—S—CH₂NHC(═O)CH₃).

It may be convenient or desirable to prepare, purify, and/or handle the active compound in the form of a prodrug. The term “prodrug”, as used herein, pertains to a compound which, when metabolised (e.g. in vivo), yields the desired active compound. Typically, the prodrug is inactive, or less active than the active compound, but may provide advantageous handling, administration, or metabolic properties.

For example, some prodrugs are esters of the active compound (e.g. a physiologically acceptable metabolically labile ester). During metabolism, the ester group (—C(═O)OR) is cleaved to yield the active drug. Such esters may be formed by esterification, for example, of any of the carboxylic acid groups (—C(═O)OH) in the parent compound, with, where appropriate, prior protection of any other reactive groups present in the parent compound, followed by deprotection if required. Examples of such metabolically labile esters include, but are not limited to, those wherein R is C₁₋₂₀ alkyl (e.g. -Me, -Et); C₁₋₇ aminoalkyl (e.g. aminoethyl; 2-(N,N-diethylamino)ethyl; 2-(4-morpholino)ethyl); and acyloxy-C₁₋₇ alkyl (e.g. acyloxymethyl; acyloxyethyl; e.g. pivaloyloxymethyl; acetoxymethyl; 1-acetoxyethyl; 1-(1-methoxy-1-methyl)ethyl-carbonxyloxyethyl; 1-(benzoyloxy)ethyl; isopropoxy-carbonyloxymethyl; 1-isopropoxy-carbonyloxyethyl; cyclohexyl-carbonyloxymethyl; 1-cyclohexyl-carbonyloxyethyl; cyclohexyloxy-carbonyloxymethyl; 1-cyclohexyloxy-carbonyloxyethyl; (4-tetrahydropyranyloxy)carbonyloxymethyl; 1-(4-tetrahydropyranyloxy)carbonyloxyethyl; (4-tetrahydropyranyl)carbonyloxymethyl; and 1-(4-tetrahydropyranyl)carbonyloxyethyl).

Further suitable prodrug forms include phosphonate and glycolate salts. In particular, hydroxy groups (—OH), can be made into phosphonate prodrugs by reaction with chlorodibenzylphosphite, followed by hydrogenation, to form a phosphonate group —O—P(═O)(OH)₂. Such a group can be cleaved by phosphatase enzymes during metabolism to yield the active drug with the hydroxy group.

Also, some prodrugs are activated enzymatically to yield the active compound, or a compound which, upon further chemical reaction, yields the active compound. For example, the prodrug may be a sugar derivative or other glycoside conjugate, or may be an amino acid ester derivative.

Acronyms

For convenience, many chemical moieties are represented using well known abbreviations, including but not limited to, methyl (Me), ethyl (Et), n-propyl (nPr), iso-propyl (iPr), n-butyl (nBu), tert-butyl (tBu), n-hexyl (nHex), cyclohexyl (cHex), phenyl (Ph), biphenyl (biPh), benzyl (Bn), naphthyl (naph), methoxy (MeO), ethoxy (EtO), benzoyl (Bz), and acetyl (Ac).

For convenience, many chemical compounds are represented using well known abbreviations, including but not limited to, methanol (MeOH), ethanol (EtOH), iso-propanol (i-PrOH), methyl ethyl ketone (MEK), ether or diethyl ether (Et₂O), acetic acid (AcOH), dichloromethane (methylene chloride, DCM), trifluoroacetic acid (TFA), dimethylformamide (DMF), tetrahydrofuran (THF), and dimethylsulfoxide (DMSO).

Synthesis

Compounds of formula I of the present invention:

can be synthesized from a precursor of formula 2:

, where OProt represents a protected hydroxy group. The various substituent groups shown may be the same as defined for compounds of formula I, or may be protected versions or precursors of those defined groups, such that further transformation is needed to reach the desired compound. The synthesis of the compounds of the invention can proceed by removal of the hydroxy protecting group followed by amide bond formation, using standard techniques, e.g. base catalysation, HBTU coupling.

The compounds of formula 2 can be synthesized by coupling a compound of formula 3 or formula 4:

with a compound of formula 5 or 6 respectively:

The urea bond formation reaction is carried out under standard conditions. Compounds of formulae 5 and 6 may be synthesized according to known methods, and examples are given below. The same applies to compounds of formulae 3 and 4.

Use

The present invention provides active compounds, specifically, active in inhibiting the activity of PARP-1.

The term “active” as used herein, pertains to compounds which are capable of inhibiting PARP-1 activity, and specifically includes both compounds with intrinsic activity (drugs) as well as prodrugs of such compounds, which prodrugs may themselves exhibit little or no intrinsic activity.

One assay which may conveniently be used in order to assess the PARP-1 inhibition offered by a particular compound is described in the examples below.

The present invention further provides a method of inhibiting the activity of PARP-1 in a cell, comprising contacting said cell with an effective amount of an active compound, preferably in the form of a pharmaceutically acceptable composition. Such a method may be practiced in vitro or in vivo.

For example, a sample of cells may be grown in vitro and an active compound brought into contact with said cells, and the effect of the compound on those cells observed. As examples of “effect”, the amount of DNA repair effected in a certain time may be determined. Where the active compound is found to exert an influence on the cells, this may be used as a prognostic or diagnostic marker of the efficacy of the compound in methods of treating a patient carrying cells of the same cellular type.

The term “treatment”, as used herein in the context of treating a condition, pertains generally to treatment and therapy, whether of a human or an animal (e.g. in veterinary applications), in which some desired therapeutic effect is achieved, for example, the inhibition of the progress of the condition, and includes a reduction in the rate of progress, a halt in the rate of progress, amelioration of the condition, and cure of the condition. Treatment as a prophylactic measure (i.e. prophylaxis) is also included.

The term “adjunct” as used herein relates to the use of active compounds in conjunction with known therapeutic means. Such means include cytotoxic regimens of drugs and/or ionising radiation as used in the treatment of different cancer types. In particular, the active compounds are known to potentiate the actions of a number of cancer chemotherapy treatments, which include the topoisomerase class of poisons and most of the known alkylating agents used in treating cancer.

Active compounds may also be used as cell culture additives to inhibit PARP, for example, in order to sensitize cells to known chemotherapeutic agents or ionising radiation treatments in vitro.

Active compounds may also be used as part of an in vitro assay, for example, in order to determine whether a candidate host is likely to benefit from treatment with the compound in question.

Administration

The active compound or pharmaceutical composition comprising the active compound may be administered to a subject by any convenient route of administration, whether systemically/peripherally or at the site of desired action, including but not limited to, oral (e.g. by ingestion); topical (including e.g. transdermal, intranasal, ocular, buccal, and sublingual); pulmonary (e.g. by inhalation or insufflation therapy using, e.g. an aerosol, e.g. through mouth or nose); rectal; vaginal; parenteral, for example, by injection, including subcutaneous, intradermal, intramuscular, intravenous, intraarterial, intracardiac, intrathecal, intraspinal, intracapsular, subcapsular, intraorbital, intraperitoneal, intratracheal, subcuticular, intraarticular, subarachnoid, and intrasternal; by implant of a depot, for example, subcutaneously or intramuscularly.

The subject may be a eukaryote, an animal, a vertebrate animal, a mammal, a rodent (e.g. a guinea pig, a hamster, a rat, a mouse), murine (e.g. a mouse), canine (e.g. a dog), feline (e.g. a cat), equine (e.g. a horse), a primate, simian (e.g. a monkey or ape), a monkey (e.g. marmoset, baboon), an ape (e.g. gorilla, chimpanzee, orangutang, gibbon), or a human.

Formulations

While it is possible for the active compound to be administered alone, it is preferable to present it as a pharmaceutical composition (e.g., formulation) comprising at least one active compound, as defined above, together with one or more pharmaceutically acceptable carriers, adjuvants, excipients, diluents, fillers, buffers, stabilisers, preservatives, lubricants, or other materials well known to those skilled in the art and optionally other therapeutic or prophylactic agents.

Thus, the present invention further provides pharmaceutical compositions, as defined above, and methods of making a pharmaceutical composition comprising admixing at least one active compound, as defined above, together with one or more pharmaceutically acceptable carriers, excipients, buffers, adjuvants, stabilisers, or other materials, as described herein.

The term “pharmaceutically acceptable” as used herein pertains to compounds, materials, compositions, and/or dosage forms which are, within the scope of sound medical judgement, suitable for use in contact with the tissues of a subject (e.g. human) without excessive toxicity, irritation, allergic response, or other problem or complication, commensurate with a reasonable benefit/risk ratio. Each carrier, excipient, etc. must also be “acceptable” in the sense of being compatible with the other ingredients of the formulation.

Suitable carriers, diluents, excipients, etc. can be found in standard pharmaceutical texts. See, for example, “Handbook of Pharmaceutical Additives”, 2nd Edition (eds. M. Ash and 1. Ash), 2001 (Synapse Information Resources, Inc., Endicott, N.Y., USA), “Remington's Pharmaceutical Sciences”, 20th edition, pub. Lippincott, Williams & Wilkins, 2000; and “Handbook of Pharmaceutical Excipients”, 2nd edition, 1994.

The formulations may conveniently be presented in unit dosage form and may be prepared by any methods well known in the art of pharmacy. Such methods include the step of bringing into association the active compound with the carrier which constitutes one or more accessory ingredients. In general, the formulations are prepared by uniformly and intimately bringing into association the active compound with liquid carriers or finely divided solid carriers or both, and then if necessary shaping the product.

Formulations may be in the form of liquids, solutions, suspensions, emulsions, elixirs, syrups, tablets, losenges, granules, powders, capsules, cachets, pills, ampoules, suppositories, pessaries, ointments, gels, pastes, creams, sprays, mists, foams, lotions, oils, boluses, electuaries, or aerosols.

Formulations suitable for oral administration (e.g., by ingestion) may be presented as discrete units such as capsules, cachets or tablets, each containing a predetermined amount of the active compound; as a powder or granules; as a solution or suspension in an aqueous or non-aqueous liquid; or as an oil-in-water liquid emulsion or a water-in-oil liquid emulsion; as a bolus; as an electuary; or as a paste.

A tablet may be made by conventional means, e.g. compression or molding, optionally with one or more accessory ingredients. Compressed tablets may be prepared by compressing in a suitable machine the active compound in a free-flowing form such as a powder or granules, optionally mixed with one or more binders (e.g. povidone, gelatin, acacia, sorbitol, tragacanth, hydroxypropylmethyl cellulose); fillers or diluents (e.g. lactose, microcrystalline cellulose, calcium hydrogen phosphate); lubricants (e.g. magnesium stearate, talc, silica); disintegrants (e.g. sodium starch glycolate, cross-linked povidone, cross-linked sodium carboxymethyl cellulose); surface-active or dispersing or wetting agents (e.g., sodium lauryl sulfate); and preservatives (e.g., methyl p-hydroxybenzoate, propyl p-hydroxybenzoate, sorbic acid). Molded tablets may be made by molding in a suitable machine a mixture of the powdered compound moistened with an inert liquid diluent. The tablets may optionally be coated or scored and may be formulated so as to provide slow or controlled release of the active compound therein using, for example, hydroxypropylmethyl cellulose in varying proportions to provide the desired release profile. Tablets may optionally be provided with an enteric coating, to provide release in parts of the gut other than the stomach.

Formulations suitable for topical administration (e.g. transdermal, intranasal, ocular, buccal, and sublingual) may be formulated as an ointment, cream, suspension, lotion, powder, solution, past, gel, spray, aerosol, or oil. Alternatively, a formulation may comprise a patch or a dressing such as a bandage or adhesive plaster impregnated with active compounds and optionally one or more excipients or diluents.

Formulations suitable for topical administration in the mouth include losenges comprising the active compound in a flavored basis, usually sucrose and acacia or tragacanth; pastilles comprising the active compound in an inert basis such as gelatin and glycerin, or sucrose and acacia; and mouthwashes comprising the active compound in a suitable liquid carrier.

Formulations suitable for topical administration to the eye also include eye drops wherein the active compound is dissolved or suspended in a suitable carrier, especially an aqueous solvent for the active compound.

Formulations suitable for nasal administration, wherein the carrier is a solid, include a coarse powder having a particle size, for example, in the range of about 20 to about 500 microns which is administered in the manner in which snuff is taken, i.e. by rapid inhalation through the nasal passage from a container of the powder held close up to the nose. Suitable formulations wherein the carrier is a liquid for administration as, for example, nasal spray, nasal drops, or by aerosol administration by nebuliser, include aqueous or oily solutions of the active compound.

Formulations suitable for administration by inhalation include those presented as an aerosol spray from a pressurised pack, with the use of a suitable propellant, such as dichlorodifluoromethane, trichlorofluoromethane, dichoro-tetrafluoroethane, carbon dioxide, or other suitable gases.

Formulations suitable for topical administration via the skin include ointments, creams, and emulsions. When formulated in an ointment, the active compound may optionally be employed with either a paraffinic or a water-miscible ointment base. Alternatively, the active compounds may be formulated in a cream with an oil-in-water cream base. If desired, the aqueous phase of the cream base may include, for example, at least about 30% w/w of a polyhydric alcohol, i.e., an alcohol having two or more hydroxyl groups such as propylene glycol, butane-1,3-diol, mannitol, sorbitol, glycerol and polyethylene glycol and mixtures thereof. The topical formulations may desirably include a compound which enhances absorption or penetration of the active compound through the skin or other affected areas. Examples of such dermal penetration enhancers include dimethylsulfoxide and related analogues.

When formulated as a topical emulsion, the oily phase may optionally comprise merely an emulsifier (otherwise known as an emulgent), or it may comprises a mixture of at least one emulsifier with a fat or an oil or with both a fat and an oil. Preferably, a hydrophilic emulsifier is included together with a lipophilic emulsifier which acts as a stabiliser. It is also preferred to include both an oil and a fat. Together, the emulsifier(s) with or without stabiliser(s) make up the so-called emulsifying wax, and the wax together with the oil and/or fat make up the so-called emulsifying ointment base which forms the oily dispersed phase of the cream formulations.

Suitable emulgents and emulsion stabilisers include Tween 60, Span 80, cetostearyl alcohol, myristyl alcohol, glyceryl monostearate and sodium lauryl sulphate. The choice of suitable oils or fats for the formulation is based on achieving the desired cosmetic properties, since the solubility of the active compound in most oils likely to be used in pharmaceutical emulsion formulations may be very low. Thus the cream should preferably be a non-greasy, non-staining and washable product with suitable consistency to avoid leakage from tubes or other containers. Straight or branched chain, mono- or dibasic alkyl esters such as di-isoadipate, isocetyl stearate, propylene glycol diester of coconut fatty acids, isopropyl myristate, decyl oleate, isopropyl palmitate, butyl stearate, 2-ethylhexyl palmitate or a blend of branched chain esters known as Crodamol CAP may be used, the last three being preferred esters. These may be used alone or in combination depending on the properties required. Alternatively, high melting point lipids such as white soft paraffin and/or liquid paraffin or other mineral oils can be used.

Formulations suitable for rectal administration may be presented as a suppository with a suitable base comprising, for example, cocoa butter or a salicylate.

Formulations suitable for vaginal administration may be presented as pessaries, tampons, creams, gels, pastes, foams or spray formulations containing in addition to the active compound, such carriers as are known in the art to be appropriate.

Formulations suitable for parenteral administration (e.g., by injection, including cutaneous, subcutaneous, intramuscular, intravenous and intradermal), include aqueous and non-aqueous isotonic, pyrogen-free, sterile injection solutions which may contain anti-oxidants, buffers, preservatives, stabilisers, bacteriostats, and solutes which render the formulation isotonic with the blood of the intended recipient; and aqueous and non-aqueous sterile suspensions which may include suspending agents and thickening agents, and liposomes or other microparticulate systems which are designed to target the compound to blood components or one or more organs. Examples of suitable isotonic vehicles for use in such formulations include Sodium Chloride Injection, Ringer's Solution, or Lactated Ringer's Injection. Typically, the concentration of the active compound in the solution is from about 1 ng/ml to about 10 μg/ml, for example from about 10 ng/ml to about 1 μg/ml. The formulations may be presented in unit-dose or multi-dose sealed containers, for example, ampoules and vials, and may be stored in a freeze-dried (lyophilised) condition requiring only the addition of the sterile liquid carrier, for example water for injections, immediately prior to use. Extemporaneous injection solutions and suspensions may be prepared from sterile powders, granules, and tablets. Formulations may be in the form of liposomes or other microparticulate systems which are designed to target the active compound to blood components or one or more organs.

Dosage

It will be appreciated that appropriate dosages of the active compounds, and compositions comprising the active compounds, can vary from patient to patient. Determining the optimal dosage will generally involve the balancing of the level of therapeutic benefit against any risk or deleterious side effects of the treatments of the present invention. The selected dosage level will depend on a variety of factors including, but not limited to, the activity of the particular compound, the route of administration, the time of administration, the rate of excretion of the compound, the duration of the treatment, other drugs, compounds, and/or materials used in combination, and the age, sex, weight, condition, general health, and prior medical history of the patient. The amount of compound and route of administration will ultimately be at the discretion of the physician, although generally the dosage will be to achieve local concentrations at the site of action which achieve the desired effect without causing substantial harmful or deleterious side-effects.

Administration in vivo can be effected in one dose, continuously or intermittently (e.g., in divided doses at appropriate intervals) throughout the course of treatment. Methods of determining the most effective means and dosage of administration are well known to those of skill in the art and will vary with the formulation used for therapy, the purpose of the therapy, the target cell being treated, and the subject being treated. Single or multiple administrations can be carried out with the dose level and pattern being selected by the treating physician.

In general, a suitable dose of the active compound is in the range of about 100 μg to about 250 mg per kilogram body weight of the subject per day. Where the active compound is a salt, an ester, prodrug, or the like, the amount administered is calculated on the basis of the parent compound and so the actual weight to be used is increased proportionately.

EXAMPLES General Experimental Methods Preparative HPLC

Samples were purified with a Waters mass-directed purification system utilising a Waters 600 LC pump, Genesis AQ 120A 4μ 500 mm×4.6 mm column and Micromass ZQ mass spectrometer, operating in positive ion electrospray ionisation mode. Mobile phases A (0.1% formic acid in water) and B (0.1% formic acid in acetonitrile) were used in a gradient:

Time (mins) % B 0 0 1 0 7 95 9 95 10 0 15 0

Flow rate: 2.0 ml/min

Analytical HPLC-MS

Analytical HPLC was typically carried out with a Spectra System P4000 pump and Jones Genesis C18 column (4 μm, 50 mm×4.6 mm). Mobile phases A (0.1% formic acid in water) and B (0.1% formic acid in acetonitrile) were used in a gradient as described below. Detection was by a TSP UV 6000LP detector at 254 nm UV and range 210-600 nm PDA. The Mass spectrometer was a Waters ZMD LC-MS system No. LD352 operating in electrospray ionization mode.

Time (mins) % B 1 5 7 95 9 95 9.5 5 13 5

Flow rate: 1.0 ml/min

NMR

¹H NMR and ¹³C NMR were typically recorded using Bruker DPX 300 spectrometer at 300 MHz and 75 MHz respectively. Chemical shifts were reported in parts per million (ppm) on the δ scale relative to tetramethylsilane internal standard. Unless stated otherwise all samples were dissolved in DMSO-d₆.

Example 1

Compound 1 was synthesised as described in Example 23, of WO 03/093261, which is incorporated herein by reference.

(a) 4-(4-Fluoro-3-isocyanato-benzyl)-2H-phthalazin-1-one (2)

To a suspension of 4-(3-amino-4-fluoro-benzyl)-2H-phthalazin-1-one (1)(4.0 g, 14.8 mmol) in anhydrous DCM (1.6 L) and triethylamine (4.62 mL, 40.86 mmol), was added a dropwise preformed solution of triphosgene (2.75 g, 9.28 mmol) in anhydrous DCM (327 mL) and stirred for 70 minutes and room temperature. The reaction mixture was then concentrated to dryness in vacuo yielding a grey solid. Single peak in LC-MS analysis, (yield taken to be quantitative) no purification performed. m/z (LC-MS, ESP), RT=4.49 mins, (M+MeOH) 328.0.

(b) {3-[2-Fluoro-5-(4-oxo-3,4-dihydro-phthalazin-1-ylmethyl)-phenyl]-ureido}-Amino ethyl ester (4)

To a solution of appropriate amino ester (3)(0.026 g, 0.17 mmol) in anhydrous DCM (16.7 mL) was added triethyl amine (24 μL, 0.170 mmol) and 4-(4-fluoro-3-isocyanato-benzyl)-2H-phthalazin-1-one (2)(0.05 g, 0.17 mmol). The reaction mixture was stirred for 2 hours and then washed with water (2×15 mL) and dried over MgSO₄ filtered and concentrated to afford the corresponding ureido ester. The corresponding ureido esters were used without need for purification.

(c) 3-[2-Fluoro-5-(4-oxo-3,4-dihydro-phthalazin-1-ylmethyl)-phenyl]-substituted imidazolidine-2,4-dione (5)

(i) Base catalyzed method (5a-5e,5g-5i)

To the appropriate {3-[2-fluoro-5-(4-oxo-3,4-dihydro-phthalazin-1-ylmethyl)-phenyl]-ureido ester (4)(0.065 mmol) in anhydrous dimethylacetimide (0.5 mL) was added, sodium hydroxide (2.6 mg, 0.065 mmol) and heated to 50° C. for 30 minutes. The reaction mixture was then diluted with DCM (2 mL) and washed with brine (2.5 ml). The crude samples were submitted for preparative HPLC.

(ii) HBTU Coupling Method (5f, 5j)

To {3-[2-fluoro-5-(4-oxo-3,4-dihydro-phthalazin-1-ylmethyl)-phenyl]-ureido ester (4)(0.065 mmol) in ethanol (0.5 mL) was added, sodium hydroxide (2.6 mg, 0.065 mmol) and stirred at room temperatyre for 30 minutes. The reaction mixture was then neutralized by addition of hydrochloric acid (0.065 mmol) and concentrated to dryness in vacuo.

The resulting solid was then suspended in DCM (0.5 mL) and treated with N′N′diisopropylethylamine (10.5 μL, 0.06 mmol) and 2-(1H-benzotriazole-1-yl)-1,1,3,3-tetramethyluronium hexafluorophosphate (0.024 g, 0.06 mmol). The reaction mixture was stirred for 18 hours and then submitted for preparative HPLC.

Pur- Com- ity Rt pound R^(D) (%) (min) M + H 5a

71 3.92 395.4 5b

92 3.81 367.4 5c

96 6.72 353.3 5d

96 7.73 381.4 5e

99 7.16 367.4 5f

93 6.53 368.3 5g

99 4.78 482.5 5h

79 8.78 427.5 5i

94 8.39 393.4 5j

95 3.85 367.4

Example 2

Compound 6 was synthesised as described in Example 1, of WO 03/093261, which is incorporated herein by reference.

(a) 4-(3-isocyanato-benzyl)-2H-phthalazin-1-one (7)

To a solution of 4-(3-amino-benzyl)-2H-phthalazin-1-one (6)(1.0 g, 4.0 mmol) in dry DCM (415 mL) and triethylamine (1.5 mL, 10.9 mmol) was added a dropwise preformed solution of triophosgene (0.73 g, 2.5 mmol) in dry DCM (85 mL) over 30 minutes. After a further 2 hours the reaction mixture was concentrated to dryness yielding a light yellow powder. Single peak in LC-MS analysis, (yield taken to be quantitative) no purification performed; m/z (LC-MS, ESP), RT=3.90 mins, (M+MeOH) 310.0.

(b) {3-[5-(4-oxo-3,4-dihydro-phthalazin-1-ylmethyl)-phenyl]-ureido}-Amino ethyl ester (8)

To a solution of appropriate amino ester (0.026 g, 0.17 mmol) in anhydrous DCM (16.7 mL) was added triethylamine (24 μL, 0.170 mmol) and 4-(3-isocyanato-benzyl)-2H-phthalazin-1-one (7) (0.05 g, 0.17 mmol). The reaction mixture was stirred for 2 hours and then washed with water (2×15 mL) and dried over MgSO₄ filtered and concentrated to afford the corresponding ureido ester. The corresponding ureido esters were used without need for any purification.

(c) 3-[5-(4-oxo-3,4-dihydro-phthalazin-1-ylmethyl)-phenyl]-substituted imidazolidine-2,4-dione (9)

To the appropriate {1-[3-(4-oxo-3,4-dihydro-phthalazin-1-ylmethyl)-phenylcarbamoyl]-substituted}-carbamic esters (0.065 mmol) in anhydrous dimethylacetimide (0.5 mL) was added, sodium hydroxide (2.6 mg, 0.065 mmol) and heated to 50° C. for 0.5-6 hours. The reaction mixture was then diluted with DCM (2 mL) and washed with brine (2.5 ml). The crude samples were submitted for preparative HPLC.

Pur- Com- ity Rt pound R^(D) (%) (min) M + H 9a

93 7.08 349.4 9b

96 3.94 363.9 9c

99 4.20 335.3

Example 3

(a) Carbonylmethyl-amino acetic acid bis(tert-Butylsilyl ester) (11)

A suspension of (carboxymethyl-amino)-acetic acid (10)(0.6 g, 4.51 mmol) in bis(trimethylsilyl)-trifluoroacetamide (45 mL, 169 mmol) was heated until complete dissolution, (ca 1 hr). The reaction mixture was then concentrated in vacuo resulting in a yellow oil (1.6 g). The oil was used without need for any purification.

(b) {3-[2-Fluoro-5-(4-oxo-3,4-dihydro-phthalazin-1-ylmethyl)-phenyl]-2,4-dioxo-imidazolidin-1-yl}-acetic acid (12)

To a suspension of 4-(4-fluoro-3-isocyanato-benzyl)-2H-phthalazin-1-one (2) (4.51 mmol) in anhydrous dioxane (180 mL), was added triethylamine (617 μL, 4.51 mmol) followed by carbonylmethyl-amino acetic acid bis(tert-butylsilyl ester) (11)(1.25 g, 4.51 mmol). The suspension was stirred at room temperature for 48 hours.

The reaction mixture was concentrated to dryness and then diluted with water (150 mL) and the pH adjusted to 10 using sodium hydroxide solution (ca 2N 10 ml). Aqueous phase was then extracted with ethyl acetate (2×20 ml). The pH of the aqueous phase was acidified to 1 using (2N HCl) and extracted with ethyl acetate (2×100 mL). The latter ethyl acetate layers were then combined, dried over MgSO₄ filtered and concentrated in vacuo to afford a yellow solid. 92% peak in LC-MS analysis, (1.0 g, 57%) no purification performed. m/z (LC-MS, ESN), RT=3.47 mins, (M−H) 409.0.

(c) {3-[2-Fluoro-5-(4-oxo-3,4-dihydro-phthalazin-1-ylmethyl)-phenyl]-2,4-dioxo-imidazolidin-1-yl}-acetic amides (13)

To a suspension of {3-[2-fluoro-5-(4-oxo-3,4-dihydro-phthalazin-1-ylmethyl)-phenyl]-2,4-dioxo-imidazolidin-1-yl}-acetic acid (12)(0.05 g, 0.122 mmol) in dry DCM (0.5 mL) was added appropriate amine (0.150 mmol) together with N′N′diisopropylethylamine (0.150 mmol) and 2-(1H-benzotriazole-1-yl)-1,1,3,3-tetramethyluronium hexafluorophosphate (0.057 g, 0.150 mmol) and stirred at room temperature for 7 hours. The reaction mixture was stirred for 18 hours and then submitted for preparative HPLC.

Pur- Com- ity Rt pound R (%) (min) M + H 13a

78 3.59 481.5 13b

99 4.08 480.5 13c

94 3.60 493.5 13d

99 4.02 411.4

Example 4

(a) 2-Methyl-4-nitro-pyridin-1-ol (15)

2-Picoline-N-oxide (14)(21.9 g, 0.2 mmol) was added to a concentrated sulphuric acid (76 mL), maintaining the temperature below 40° C. The mixture was cooled to 5° C.; fuming nitric acid (60 mL) was the added dropwise over 15 minutes, maintaining reaction temperature below 10° C. After the addition was complete the reaction mixture was heated to 100° C. for 1.5 hours. The reaction was then cooled to rt and poured over ice (ca 500 g), the resultant green/yellow solution was neutralised by addition of sodium carbonate (ca 205 g over 1 hour). The mixture was then filtered and washed with water (2 L). The solid cake was then dissolved in DCM (500 mL) and dried over Na₂SO₄. Hexane (100 mL) was added to the DCM solution resulting in a yellow suspension which was filtered off and dried. Single peak in LC-MS analysis, (25.40 g 82.5%) no purification performed and taken through crude to next step.

(b) Acetic acid 4-nitro-pyridin-2-ylmethyl ester (16)

To acetic anhydride (60 mL, 0.635 mol) at 110° C. under a nitrogen atmosphere was added 2-methyl-4-nitro-pyridin-1-ol (15)(17.1 g, 111 mmol) portionwise over 1 minute. After approximately 2 minutes the solution began to darken and heating maintained at 100-120° C. for 30 minutes and then allowed to cool to 80° C. Ethanol (60 mL) was added and the solution was concentrated under vacuum; residue slurried in water (140 mL) and the mixture neutralised with NaHCO₃ (ca. 40 g). The aqueous liquor was extracted with ethyl acetate (4×100 mL, combined extracts washed with brine (2×100 mL, dried over Na₂SO₄, concentrated in vacuo to a crude oil. The material was subjected to flash chromatography eluent hexane:TBME (2:1). A brown oil was isolated, single peak in LC-MS analysis, (6.44 g 30%); m/z (LC-MS, ESP), RT=3.65 mins, (M+H) 197.

(c) (4-Nitro-pyridin-2-yl)-methanol (17)

To a solution of acetic acid 4-nitro-pyridin-2-ylmethyl ester (16)(0.49 g, 2.5 mmol) in methanol (5 mL), was added a solution of sodium hydroxide (2N, 1.6 mL) and the reaction was stirred for 30 minutes and then concentrated in vacuo. The residue was diluted with water (10 mL) and extracted with ethyl acetate (2×10 mL). The combined extracts were washed with brine (10 mL) and concentrated in vacuo to afford a crude oil which solidified upon standing. Single peak in LC-MS analysis, (0.13 g 33%); m/z (LC-MS, ESP), RT=2.67 mins, (M+H) 155.

(d) 4-Nitro-pyridine-2-carbaldehyde (18)

To cooled solution of oxalyl chloride (0.533 g, 4.18 mmol) in DCM (2 mL) at −78° C. under nitrogen was added dimethyl sulfoxide (0.593 mL, 8.37 mmol) dropwise. After 30 minutes (4-nitro-pyridin-2-yl)-methanol (17)(0.129, 0.837 mmol) in DCM (2 mL) was added dropwise maintaining temperature at −78° C. After 2 hours the mixture was warmed to −55° C. Triethylamine (1.74 mL, 12.55 mmol) was then added and the mixture allowed to warm to room temperature over 2 hours. Brine (10 mL) was then added and the mixture extracted with DCM (4×10 mL). The combined organics were then dried over MgSO₄ and concentrated in vacuo to an oil. The material was used directly without need for purification assuming quantitative conversion.

(e) 3-(4-Nitro-pyridin-2-ylmethylene)-3H-isobenzofuran-1-one (19)

To a cooled solution of (4-oxo-3,4-dihydro-phthalazin-1-yl)-phosphonic acid dimethyl ester (0.202 g, 0.837 mmol) in THF (4 mL) at 10° C. was added 4-nitro-pyridine-2-carbaldehyde (0.837 mmol) under a nitrogen atmosphere. Triethylamine (0.174 mL, 1.25 mmol) was added dropwise over 10 minutes and then allowed to stir at room temperature for 18 hours. The yellow suspension was poured in water (9 mL), and the then filtered, the solid was washed with water (2×2 mL), hexane (2×2 mL) and then diethyl ether (2×2 mL) and then dried in vacuo to afford a 0.73 g of the desired products. Two peaks in LC-MS analysis, (0.13 g, 18% two steps) and required no further purification, m/z (LC-MS, ESP), RT=4.26 mins (M+H) 269, & RT=4.52 mins (M+H) 269.

(f) 4-(4-Amino-pyridin-2-ylmethyl)-2H-phthalazin-1-one (20)

A suspension of 3-(4-nitro-pyridin-2-ylmethylene)-3H-isobenzofuran-1-one (0.67 g, 2.5 mmol) in hydrazine monohydrate (0.25 g, 5.0 mmol) was heated to 90° C. for 1 hour and then cooled to room temperature. Ethanol (5 mL) added, followed by ammonium chloride (0.16 g, 3.0 mmol) and iron powder (0.28 g, 5.0 mmol), the mixture was then heated to 90° C. for 3 hours. The reaction mixture was filtered hot through celite which was washed with ethyl acetate (20 mL). The filtered was concentrated in vacuo and then diluted with ethyl acetate (10 mL) washed with brine (10 mL), dried over magnesium, sulphate and dried in vacuo to afford the title cpd as a pale yellow powder. Single peak in LC-MS analysis, (0.20 g, 31% yield) requiring no further purification, m/z (LC-MS, ESP), RT=1.58 (M+H) 253;

(g) 1,5,5-substituted-3-[2-(4-oxo-3,4-dihydro-phthalazin-1-ylmethyl)-pyridin-4-yl]-imidazolidine-2,4-dione (23)

To a solution of appropriate amino ester isocyanate (0.026 g, 0.17 mmol) in anhydrous DCM (16.7 mL) was added triethyl amine (24 μL, 0.170 mmol) and 4-(4-amino-pyridin-2-ylmethyl)-2H-phthalazin-1-one (21)(0.05 g, 0.17 mmol). The reaction mixture was stirred for 8 hours and concentrated in vacuo to afford the corresponding ureido ester. Anhydrous dimethylacetimide (0.5 mL) was added, followed by sodium hydroxide (2.6 mg, 0.065 mmol) and the mixture heated to 50° C. for 30 minutes. The reaction mixture was then diluted with DCM (2 mL) and washed with brine (2.5 ml). The crude samples were submitted for preparative HPLC.

(xi) Alternative route to 1,5,5-substituted-3-[2-(4-oxo-3,4-dihydro-phthalazin-1-ylmethyl)-pyridin-4-yl]-imidazolidine-2,4-dione (23) (a) 4-(4-Isocyanato-pyridin-2-ylmethyl)-2H-phthalazin-1-one (22)

To a suspension of 4-(4-amino-pyridin-2-ylmethyl)-2H-phthalazin-1-one (21) (0.40 g, 1.48 mmol) in anhydrous DCM (160 mL) and triethylamine (0.46 mL, 4.09 mmol), was added a dropwise preformed solution of triphosgene (0.27 g, 0.93 mmol) in anhydrous DCM (30 mL). The reaction was stirred for 6 hrs at room temperature. The reaction mixture was then concentrated to dryness in vacuo yielding a grey solid. Single peak in LC-MS analysis, (yield taken to be quantitative) no purification performed. m/z (LC-MS, ESP), RT=3.79 mins, (M+MeOH) 329.0.

(b) To a solution of appropriate amino ester (0.026 g, 0.17 mmol) in anhydrous DCM (16.7 mL) was added triethyl amine (24 μL, 0.170 mmol) and 4-(4-isocyanato-pyridin-2-ylmethyl)-2H-phthalazin-1-one (22)(0.05 g, 0.18 mmol). The reaction mixture was stirred for 8 hrs and concentrated in vacuo to afford the corresponding crude ureido ester. Anhydrous dimethylacetimide (0.5 mL) was added, followed by sodium hydroxide (2.6 mg, 0.065 mmol) and heated to 50° C. for 30 minutes. The reaction mixture was then submitted for preparative HPLC.

Pur- Com- ity Rt pound R^(D) (%) (min) M + H 23a

91 3.43 336.32

Example 5

(a) 4-Nitro-thiophene-2-carbaldehyde (25)

To conc nitric acid (15 mL) was added conc sulphuric acid (15 mL) the mixture was cooled to −10° C. and 2-thiophencarboxyaldehyde (24)(10.0 g, 89.2 mmol) was added dropwise over 15 minutes maintaining the reaction temperature between −5° C. and 0° C. The mixture was stirred for a further 1 hour before being poured into water (200 mL) and extracted with DCM (3×100 mL). The combined organic layers were dried over MgSO₄ and concentrated in vacuo. The crude oil was subjected to flash chromatography, eluent hexane:ether 10:1. The desired isomer (rf 0.32 in 2:1 hexane:ether) was collected. Single peak in LC-MS analysis, (11.5 g, 82% yield) requiring no further purification; m/z (LC-MS, ESP), RT=3.55 mins no ionisation observed in ms; ¹H NMR (300 MHz, D₆-DMSO) 10.0 (1H, s), 9.2 (1H, s), 8.6 (1H, s).

(b) 3-(4-Nitro-thiophen-2-ylmethylene)-3H-isobenzofuran-1-one (26)

To a solution of (4-oxo-3,4-dihydro-phthalazin-1-yl)-phosphonic acid dimethyl ester (3.85 g, 15.9 mmol) in THF (30 mL) was added 4-nitro-thiophene-2-carbaldehyde (25) (2.5 g, 15.9 mmol) under nitrogen. Triethylamine (2.2 mL 15.9 mmol) was added dropwise over 10 minutes and then stirred at room temperature for 4 hours. The yellow suspension was poured in water (80 mL), and the then filtered, the solid was washed with water (15 mL), hexane (10 mL) and then diethyl ether (10 mL) and then dried in vacuo to afford a 4.1 g of the desired products. Two peaks in LC-MS analysis, (4.1 g, 94%) and required no further purification; m/z (LC-MS, ESP), RT=4.71 mins (M+H) 274, & RT=4.84 mins (M+H) 274;

(c) 4-(4-Nitro-thiophen-2-ylmethyl)-2H-phthalazin-1-one (27)

A suspension of 3-(4-nitro-thiophen-2-ylmethylene)-3H-isobenzofuran-1-one (26) (1.95 g, 5.17 mmol) in hydrazine monohydrate (0.6 mL, 12.0 mmol) was heated to 90° C. for 1 hour and then cooled to room temperature. The mixture was filtered and the filtered cake was washed with water (3×40 mL), hexane (2×40 mL) and dried in vacuo at 50° C. Two peaks in LC-MS analysis, (1.0 g, 61%) and required no further purification; m/z (LC-MS, ESP), R_(T)=4.05 mins (M+H) 289, & RT=3.71 mins (M+H) 289.

(d) 4-(4-Amino-thiophen-2-ylmethyl)-2H-phthalazin-1-one (28)

To a suspension of 4-(4-nitro-thiophen-2-ylmethyl)-2H-phthalazin-1-one (27) (0.90 g, 5.71 mmol) in ethanol (25 mL) under a nitrogen blanket was added dropwise a solution of ammonium chloride (0.31 g, 5.7 mmol) in water 18 mL). After stirring the resultant solution for 5 minutes, iron powder (0.64 g, 11.5 mmol) was added in one portion. The yellow mixture was stirred at 80° C. for 3 hours. The reaction mixture was filtered hot through celite which was washed with ethyl acetate (80 mL). The concentrated in vacuo and then diluted with ethyl acetate (20 mL) washed with brine (20 mL), dried over magnesium, sulphate and dried in vacuo to afford the title cpd as a bright yellow powder. Single peak in LC-MS analysis, (0.68 g, 84% purity and required no further purification; m/z (LC-MS, ESP), RT=2.94 (M+H) 258.

(e) Substituted {3-[5-(4-Oxo-3,4-dihydro-phthalazin-1-ylmethyl)-thiophen-3-yl]-ureido}-acetic acid ethyl ester (29)

To a suspension of 4-(4-amino-thiophen-2-ylmethyl)-2H-phthalazin-1-one (28)(75 mg, 0.29 mmol) in DCM (1.5 mL) under nitrogen was added appropriate isocyanate (0.380 mmol). After stirring for 3 hours the reaction was quenched with water and the resultant precipitate filtered and dried. The solids isolated were used without need for purification.

(f) {1-[3-(4-Oxo-3,4-dihydro-phthalazin-1-ylmethyl)phenylcarbamoyl substituted imidazolidine-2,4-dione (30)

To the appropriate {3-[5-(4-oxo-3,4-dihydro-phthalazin-1-ylmethyl)-thiophen-3-yl]-ureido}-acetic acid ethyl ester (29)(0.065 mmol) in anhydrous dimethylacetimide (0.5 mL) was added, sodium hydroxide (2.6 mg, 0.065 mmol) and heated to 50° C. for 0.5-6 hours. The reaction mixture was then diluted with DCM (2 mL) and washed with brine (2.5 ml). The crude samples were submitted for preparative HPLC.

Pur- Com- ity Rt pound R^(D) (%) (min) M + H 30a

99 4.07 355.4 30b

88 3.91 341.4

Example 6

a) 2-(Tert-butoxycarbonylmethyl-amino)-propionic acid methyl ester (33A)

To a solution of tert-butyl chloroacetate (31)(4.5 g, 29.7 mmol) in dry DMF (50 ml) was added Hunig's base (6.28 mL, 36.0 mmol) followed by potassium carbonate (5.24 g, 38.0 mmol). The mixture was heated to 90° C. before DL-alanine methyl ester (32A)(4.55 g, 37.2 mmol) dissolved in DMF (10 ml) was added dropwise over 1 hour. The heating was continued for a further 1 hour and the reaction cooled to room temperature. The reaction mixture was then diluted with water (70 ml) and extracted with DCM (3×50 ml). The combined organics were then dried over sodium sulfate and concentrated to dryness in vacuo. The resultant oil was purified by flash chromatography eluent 5:1 hexane/ethyl acetate, Rf of 0.19, staining blue with ‘Anisaldehyde stain’. 3.5 g of colourless oil was obtained. Assumed to be 100% pure and taken on to next step without any further analysis.

‘Anisaldehyde stain’ Recipe—To 135 mL of absolute ethanol was added 5 mL of concentrated sulfuric acid, 1.5 mL of glacial acetic acid and 3.7 mL of p-anisaldehyde. The solution is then stirred vigorously to ensure homogeneity.

b) {3-[2-Fluoro-5-(4-oxo-3,4-dihydro-phthalazin-1-ylmethyl)-phenyl]-5-methyl-2,4-dioxo-imidazolidin-1-yl}-acetic acid tert-butyl ester (35A)

To a suspension of 4-(3-isocyanato-benzyl)-2H-phthalazin-1-one (2)(3.12 mmol) in dry DCM (80 ml) in the presence of activated 4 Å molecular sieves (ca 5 g) was added 2-(tert-butoxycarbonylmethyl-amino)-propionic acid methyl ester (33A)(1.07 g, 4.7 mmol). The reaction was then stirred for 48 hours at ambient temperature. HPLC analysis showed there to a mixture of cyclised and uncyclised ureas 1:1 ratio. The mixture was filtered and concentrated in vacuo. The crude oil was then subjected to flash chromatography eluent: 1:1 hexane ethyl acetate, Rf=0.09. Single peak in LC-MS analysis, (1.3 g, 95% purity) and required no further purification; m/z (LC-MS, ESP), RT=3.66 mins (M+H) 481—compound cyclised on column

c) {3-[2-Fluoro-5-(4-oxo-3,4-dihydro-phthalazin-1-ylmethyl)-phenyl]-5-methyl-2,4-dioxo-imidazolidin-1-yl}-acetic acid (36A)

To a solution of {3-[2-fluoro-5-(4-oxo-3,4-dihydro-phthalazin-1-ylmethyl)-phenyl]-5-methyl-2,4-dioxo-imidazolidin-1-yl}-acetic acid tert-butyl ester (35A)(1.3 g, 2.7 mmol) in dry DCM (20 ml) was added trifluoroacetic acid (2 mL, ca 27 mmol) dropwise over 2 minutes. After overnight stirring the reaction mixture was concentrated to dryness and subjected to flash chromatography. Eluent 1% acetic acid in ethyl acetate. The title compound was isolated as a white solid. Single peak in LC-MS analysis, (0.680 mg, 100% purity) and required no further purification; m/z (LC-MS, ESN), RT=2.95 mins (M−H) 423

d) Synthesis of Library Compounds

To a suspension of {3-[2-Fluoro-5-(4-oxo-3,4-dihydro-phthalazin-1-ylmethyl)-phenyl]-5-methyl-2,4-dioxo-imidazolidin-1-yl}-acetic acid (36A)(145 mg, 0.34 mmol) in DCM (5 ml) was added HBTU (0.32 g, 0.85 mmol), Hunig's base (0.85 mmol) and appropriate amine (0.85 mmol). The reaction mixture was stirred for 18 hours and then the resulting compounds were purified by preparative HPLC.

Pur- Com- ity Rt pound R^(N) (%) (min) M + H 37Aa

99 4.11 494.2 37Ab

100 4.22 522.4 37Ac

98 4.36 478.3

e) An analagous route using 2-amino-2-methyl-propionic acid methyl ester instead of DL-alanine methyl ester lead to {3-[2-Fluoro-5-(4-oxo-3,4-dihydro-phthalazin-1-ylmethyl)-phenyl]-5,5-dimethyl-2,4-dioxo-imidazolidin-1-yl}-acetic acid (36B), which was then coupled to the appropriate amine as discussed in part d) above. The resulting compounds were purified by preparative HPLC.

Pur- Com- ity Rt pound R^(N) (%) (min) M + H 37Ba

99 4.32 508.2 37Bb

100 4.23 522.4 37Bc

98 4.57 492.3 37Bd

100 4.17 508.3 37Be

100 4.31 536.4 37Bf

100 4.71 536.4 37Bg

100 3.97 589.5 37Bh

99 3.92 565.4 37Bi

100 3.87 521.4 37Bj

94 6.33* 578.4 37Bk

98 3.87 565.4 37B1

100 3.90 591.4 *long method: Waters ZQ LC-MS system No. LAA 254 operating in Electrospray ionisation mode; Mobile Phase A: 0.1% Formic acid in water; Mobile Phase B: 0.1% Formic acid in acetonitrile; Column: Genesis C18 4 μm 50 × 4.6 mm

Gradient:

Time (mins.) % B 2 5 20 95 23 95 24 5 25 5

Flow rate: 2.0 ml/min.

f) 1-[2-Fluoro-5-(4-oxo-3,4-dihydro-phthalazin-1-ylmethyl)-phenyl]1-[1,3,5]triazinane-2,4,6-trione (38)

To a suspension of 4-(3-isocyanato-benzyl)-2H-phthalazin-1-one (2)(0.37 mmol) in dry DMA (1 ml) was added ethyl allophanate (52 mg, 0.34 g). The suspension was heated to 160° C. for 1 hour and then cooled to room temperature affording a dark brown suspension. The solid was filtered and sampled showing this to be approximately 80% pure RT=3.56 mins. The material was then purified by preparative HPLC purification.

Purity (%) Rt (min) M + H 90 6.66* 382.3 *long method (see above)

g) 2-{3-[2-Fluoro-5-(4-oxo-3,4-dihydro-phthalazin-1-ylmethyl)-phenyl]-5-methyl-2,4-dioxo-imidazolidin-1-yl}-acetamide (40a)

(i) {3-[2-Fluoro-5-(4-oxo-3,4-dihydro-phthalazin-1-ylmethyl)-phenyl]-5-methyl-2,4-dioxo-imidazolidin-1-yl}-acetic acid methyl ester (39)

To a solution of {3-[2-fluoro-5-(4-oxo-3,4-dihydro-phthalazin-1-ylmethyl)-phenyl]-5-methyl-2,4-dioxo-imidazolidin-1-yl}-acetic acid (36A)(0.04 g, 0.094 mmol) in methanol (4 ml) was added concentrated sulfuric acid (1 ml) and stirred at 70° C. for 90 minutes before being cooled to room temperature. The reaction mixture was then concentrated in vacuo, diluted with water (10 ml) an extracted with ethyl acetate (2×10 ml). The organic layer was then dried over sodium sulfate and concentrated in vacuo to afford a colourless oil. Single peak in LC-MS, (52 mg, 95% purity) and required no further purification; m/z (LC-MS, ESP), RT=3.24 mins (M+H) 439;

(ii) {3-[2-Fluoro-5-(4-oxo-3,4-dihydro-phthalazin-1-ylmethyl)-phenyl]-5 methyl-2,4-dioxo-imidazolidin-1-yl}-acetic acid (40a)

{3-[2-Fluoro-5-(4-oxo-3,4-dihydro-phthalazin-1-ylmethyl)-phenyl]-5-methyl-2,4-dioxo-imidazolidin-1-yl}-acetic acid methyl ester (39)(0.03 g, 0.068 mmol) was dissolved in solution of 7N ammonia in methanol (2 ml, 14 mmol) and placed in a sealed tube. The reaction was then heated to 60° C. for 18 hours. The resultant solution was concentrated in vacuo absorbed onto a 1 ml silica cartridge. The material was eluted with neat ethyl acetate. RF of 0.65 yielding pure amide product. Single peak in LC-MS, (8 mg, 100% purity) and required no further purification; m/z (LC-MS, ESP), RT=2.84 mins (M+H) 424;

h) 2-{3-[2-Fluoro-5-(4-oxo-3,4-dihydro-phthalazin-1-ylmethyl)-phenyl]-5-methyl-2,4-dioxo-imidazolidin-1-yl}-N-methyl-acetamide (40b) and 2-{3-[2-Fluoro-5-(4-oxo-3,4-dihydro-phthalazin-1-ylmethyl)-phenyl]-5-methyl-2,4-dioxo-imidazolidin-1-yl}-N,N-dimethyl-acetamide (40c)

To a suspension of {3-[2-fluoro-5-(4-oxo-3,4-dihydro-phthalazin-1-ylmethyl)-phenyl]-5-methyl-2,4-dioxo-imidazolidin-1-yl}-acetic acid (36A), (14 mg, 0.032 mmol) in DCM (0.5 ml) was added HBTU (15 mg, 0.04 mmol), Hunig's base (0.85 mmol) and the appropriate amine (0.05 mmol). The reaction mixture was stirred for 18 hours and then submitted for preparative HPLC purification.

Pur- Com- ity Rt pound R^(N) (%) (min) M + H 40b

50 7.25* 438.3 40c

85 7.65* 452.3 *long method (see above)

i) 2-{3-[2-Fluoro-5-(4-oxo-3,4-dihydro-phthalazin-1-ylmethyl)-phenyl]-5,5-dimethyl-2,4-dioxo-imidazolidin-1-yl}-acetamide (40d)

(i) {3-[2-Fluoro-5-(4-oxo-3,4-dihydro-phthalazin-1-ylmethyl)-phenyl]-5,5-dimethyl-2,4-dioxo-imidazolidin-1-yl}-acetic acid methyl ester

To a solution of {3-[2-fluoro-5-(4-oxo-3,4-dihydro-phthalazin-1-ylmethyl)-phenyl]-5,5-dimethyl-2,4-dioxo-imidazolidin-1-yl}-acetic acid (36B)(0.044 g, 0.10 mmol) in methanol (2 ml) was added concentrated sulfuric acid (0.25 ml) and heated at 70° C. for 90 minutes before being cooled to rt. The reaction mixture was then concentrated in vacuo, diluted with water (5 ml) an extracted with ethyl acetate (2×10 ml). The organic layer was then dried over magnesium sulfate and concentrated in vacuo to afford a colourless oil. Single peak in LC-MS, (42 mg, 91% purity) and required no further purification; m/z (LC-MS, ESP), RT=3.31 mins (M+H) 453;

(ii) 2-{3-[2-Fluoro-5-(4-oxo-3,4-dihydro-phthalazin-1-ylmethyl)-phenyl]-5,5-dimethyl-2,4-dioxo-imidazolidin-1-yl}-acetamide (40d)

{3-[2-Fluoro-5-(4-oxo-3,4-dihydro-phthalazin-1-ylmethyl)-phenyl]-5,5-dimethyl-2,4-dioxo-imidazolidin-1-yl}-acetic acid methyl ester (0.025 g, 0.055 mmol) was dissolved in solution of 7N ammonia in methanol (3 ml, 21 mmol) and heated in a sealed tube at 60° C. for 18 hours. The resultant solution was concentrated in vacuo and submitted for preparative HPLC purification.

Purity (%) Rt (min) M + H 96 7.26* 438.3 *long method (see above)

j) 2-{3-[2-Fluoro-5-(4-oxo-3,4-dihydro-phthalazin-1-ylmethyl)-phenyl]-5,5-dimethyl-2,4-dioxo-imidazolidin-1-yl}-N-methyl-acetamide (40e) and 2-{3-[2-fluoro-5-(4-oxo-3,4-dihydro-phthalazin-1-ylmethyl)-phenyl]-5,5-dimethyl-2,4-dioxo-imidazolidin-1-yl}-N,N-dimethyl-acetamide (40f)

To a suspension of {3-[2-fluoro-5-(4-oxo-3,4-dihydro-phthalazin-1-ylmethyl)-phenyl]-5,5-dimethyl-2,4-dioxo-imidazolidin-1-yl}-acetic acid (36B)(20 mg, 0.045 mmol) in DCM (1 ml) was added HBTU (19 mg, 0.05 mmol), Hunig's base (0.85 mmol) and appropriate amine (0.06 mmol). The reaction mixture was stirred for 18 hours and then submitted for preparative HPLC purification.

Pur- Com- ity Rt pound R^(N) (%) (min) M + H 40e

99 7.52* 452.3 40f

99 7.87* 466.2 *long method (see above)

Example 7

(a) 2-{3-[2-Fluoro-5-(4-oxo-3,4-dihydro-phthalazin-1-ylmethyl)-phenyl]-ureido}succinic acid (42)

(i) To a suspension of 4-(3-isocyanato-benzyl)-2H-phthalazin-1-one (2)(1.4 g, 4.75 mmol) in dry DCM (30 ml) in the presence of activated 4 Å molecular sieves (ca 2 g) was added DL-aspartic acid (0.60 g, 5.0 mmol), followed by triethylamine (10.0 mmol). The reaction was stirred at room temperature for 18 hours. The reaction mixture was then diluted with bicarbonate solution (20 ml) and the mixture filtered removing undesired urea byproduct. The aqueous phase contained the title compound and was washed with DCM (2×10 ml). The aqueous layer was then concentrated in vacuo to afford a beige solid, HPLC showed this to be a mixture of components (41 & 42).

(ii) The mixture of components (41 & 42) were diluted with water (100 ml) and HCl (ca 1 ml, 1 N) and heated in an open beaker, evaporating to dryness. This afforded a brown solid LC-MS greater than 90% pure for the title compound. Single peak in LC-MS, (1.8 g, 90% purity) and required no further purification; m/z (LC-MS, ESP), RT=3.54 mins (M+H) 411.

(b) Synthesis of Library Compounds

To a suspension of {1-[2-fluoro-5-(4-oxo-3,4-dihydro-phthalazin-1-ylmethyl)-phenyl]-2,5-dioxo-imidazolidin-4-yl}-acetic acid (42)(145 mg, 0.34 mmol) in DCM (5 ml) was added HBTU (0.32 g, 0.85 mmol), Hunig's base (0.85 mmol) and appropriate amine (0.85 mmol). The reaction mixture was stirred for 18 hours at room temperature and then purified by preparative HPLC purification.

Pur- Com- ity Rt pound R^(N) (%) (min) M + H 43a

99 4.50 508.3 43b

3.91 3.91 561.3 43c

97 3.83 537.4 43d

98 3.79 493.3 43e

89 3.72 550.4 43f

99 3.80 537.4 43g

97 3.82 563.4 43h

97 4.22 480.3

Example 8

(a) 2-{3-[2-Fluoro-5-(4-oxo-3,4-dihydro-phthalazin-1-ylmethyl)-phenyl]-urido}-propionic acid (45)

To a suspension of 4-(3-isocyanato-benzyl)-2H-phthalazin-1-one (2)(1.4 g, 4.7 mmol) in dry DCM (40 ml) was added D-aspartic acid (0.455 g, 5.0 mmol), followed by triethylamine (1.4 ml, 10.0 mmol). The reaction was stirred at room temperature for 4 days. The reaction mixture was then filtered. The filtrate was then diluted with water (20 ml) and washed twice with DCM (2×20 ml). The combined DCM layers were dried over sodium sulfate and then concentrated in vacuo to afford a crude oil which was subjected to flash chromatography eluent neat ethyl acetate to remove impurity and the then 1:1 ethyl acetate/methanol to remove the desired component. (Rf of 0.2 in 1:1 ethyl acetate methanol). Single peak in LC-MS analysis, (0.79 g) requiring no further purification; m/z (LC-MS, ESP), RT=2.70 (M+H) 384;

(b) 3-[2-Fluoro-5-(4-oxo-3,4-dihydro-phthalazin-1-ylmethyl)-phenyl]-5-methyl-imidazolidine-2,4-dione (5b)

To a premixed solution of trimethyl acetyl chloride (240 mg, 2.0 mmol) and triethylamine (0.35 ml, 2.5 mmol) was added 2-{3-[2-fluoro-5-(4-oxo-3,4-dihydro-phthalazin-1-ylmethyl)-phenyl]-urido}-propionic acid (45)(0.76 g, 2.0 mmol). The reaction was stirred at room temperature for 4 days at room temperature with slow progression to the desired product. The reaction mixture was then concentrated in vacuo and the crude material was submitted for preparative HPLC (40 mg isolated, 95% purity, RT (mins): 4.35)

Example 9

In order to assess the inhibitory action of the compounds, the following assay was used to determine IC₅₀ values (Dillon, et al., JBS., 8(3), 347-352 (2003)).

Mammalian PARP, isolated from Hela cell nuclear extract, was incubated with Z-buffer (25 mM Hepes (Sigma); 12.5 mM MgCl₂ (Sigma); 50 mM KCl (Sigma); 1 mM DTT (Sigma); 10% Glycerol (Sigma) 0.001% NP-40 (Sigma); pH 7.4) in 96 well FlashPlates (TRADE MARK) (NEN, UK) and varying concentrations of said inhibitors added. All compounds were diluted in DMSO and gave final assay concentrations of between 10 and 0.01 μM, with the DMSO being at a final concentration of 1% per well. The total assay volume per well was 40 μl.

After 10 minutes incubation at 30° C. the reactions were initiated by the addition of a 10 μl reaction mixture, containing NAD (5 μM), ³H-NAD and 30mer double stranded DNA-oligos. Designated positive and negative reaction wells were done in combination with compound wells (unknowns) in order to calculate % enzyme activities. The plates were then shaken for 2 minutes and incubated at 30° C. for 45 minutes.

Following the incubation, the reactions were quenched by the addition of 50 μl 30% acetic acid to each well. The plates were then shaken for 1 hour at room temperature.

The plates were transferred to a TopCount NXT (TRADE MARK) (Packard, UK) for scintillation counting. Values recorded are counts per minute (cpm) following a 30 second counting of each well.

The % enzyme activity for each compound is then calculated using the following equation:

${\% \mspace{14mu} {Inhibition}} = {100 - \left( {100 \times \frac{\left( {{{cpm}\mspace{14mu} {of}\mspace{14mu} {unknowns}} - {{mean}\mspace{14mu} {negative}\mspace{14mu} {cpm}}} \right)}{\left( {{{mean}\mspace{14mu} {positive}\mspace{14mu} {cpm}} - {{mean}\mspace{14mu} {negative}\mspace{14mu} {cpm}}} \right)}} \right)}$

IC₅₀ values (the concentration at which 50% of the enzyme activity is inhibited) were calculated, which are determined over a range of different concentrations, normally from 10 μM down to 0.001 μM. Such IC₅₀ values are used as comparative values to identify increased compound potencies.

All compounds tested had an IC₅₀ of less than 0.1 μM. The following compounds had an IC₅₀ of less than 0.01 μM: 5e-5j,9a, 9c, 13a-d, 35B, 37Aa-Ac, 37Ba, 37Bb, 37Be-Bg, 37Bi, 37Bl, 39, 40a, 43a, 43c, 43d, 43f, 43 g, 5b′.

The Potentiation Factor (PF₅₀) for compounds is calculated as a ratio of the IC₅₀ of control cell growth divided by the IC₅₀ of cell growth+PARP inhibitor. Growth inhibition curves for both control and compound treated cells are in the presence of the alkylating agent methyl methanesulfonate (MMS). The test compounds were used at a fixed concentration of 0.2 or 0.5 micromolar. The concentrations of MMS were over a range from 0 to 10 μg/ml. Cell growth was assessed using the sulforhodamine B (SRB) assay (Skehan, P., et al., (1990) New colorimetric cytotoxicity assay for anticancer-drug screening. J. Natl. Cancer Inst. 82, 1107-1112). 2,000 HeLa cells were seeded into each well of a flat-bottomed 96-well microtiter plate in a volume of 100 μl and incubated for 6 hours at 37° C. Cells were either replaced with media alone or with media containing PARP inhibitor at a final concentration of 0.5, 1 or 5 μM. Cells were allowed to grow for a further 1 hour before the addition of MMS at a range of concentrations (typically 0, 1, 2, 3, 5, 7 and 10 μg/ml) to either untreated cells or PARP inhibitor treated cells. Cells treated with PARP inhibitor alone were used to assess the growth inhibition by the PARP inhibitor.

Cells were left for a further 16 hours before replacing the media and allowing the cells to grow for a further 72 hours at 37° C. The media was then removed and the cells fixed with 100 μl of ice cold 10% (w/v) trichloroacetic acid. The plates were incubated at 4° C. for 20 minutes and then washed four times with water. Each well of cells was then stained with 100 μl of 0.4% (w/v) SRB in 1% acetic acid for 20 minutes before washing four times with 1% acetic acid. Plates were then dried for 2 hours at room temperature. The dye from the stained cells was solubilized by the addition of 100 μl of 10 mM Tris Base into each well. Plates were gently shaken and left at room temperature for 30 minutes before measuring the optical density at 564 nM on a Microquant microtiter plate reader.

Most of the compounds tested had a PF₅₀ at 200 nM of 1 or more.

Solubility Assay

A typical assay that may be used to assess the solubility of the compounds of the present invention is as follows. The solubility of the compound is assessed in water and phosphate-buffered saline (pbs) at pH 7.4. The samples are all allowed to equilibriate in the solvent (with shaking) for 20 hours at room temperature. After that period, the samples will be visually examined to determine the presence/absence of un-dissolved solid. The samples will be centrifuged or filtered as necessary to remove insoluble material, and the solution analysed to determine solubility of the DS, diluting both aqueous and DMSO samples to a similar concentration with DMSO. The area of the peak obtained by HPLC (using the diode array detector) from the sample will be compared to the area of the peak from the DMSO solution (diluted to the same concentration as the sample) and quantified taking into account the weight of sample taken for initial dissolution. The assumption is made that the sample will be completely soluble in DMSO at the levels used for testing.

Comparing the ratio of the peak areas, and knowing the concentration of the original samples, the solubility may be calculated.

Preparation of Samples

About 1 mg of the sample is weighed accurately into a 4-ml glass vial and exactly 1.0 ml of water, aqueous buffer or DMSO, is added to it by pipette. Each vial is ultrasonicated for up to 2 minutes to assist solublisation of the solid. The samples are retained at room temperature for 20 hours, shaking on an orbital shaker. The vials are examined after this period to determine the presence/absence of un-dissolved solid. The samples should be centrifuged, or filtered through a 0.45 μm filter, to remove insoluble material if necessary, and the filtrate analysed to determine concentration of the compound in solution, after diluting all samples as appropriate with DMSO. 20 μl is injected onto the HPLC using the method shown below, injecting all samples in duplicate. The maximum solubility that can be determined using this method is nominally 1.0 mg/ml, the weight taken divided by the volume of solvent used.

Analytical Techniques

The samples are subjected to LC/MS using a Waters Micromass ZQ instrument (or equivalent) with test parameters typically as follows.

Waters Micromass ZQ in positive ion mode.

Scanning from m/z 100 to 800

Mobile phase A—0.1% aqueous formic acid

Mobile phase B—0.1% formic acid in Acetonitrile

Column—Jones Chromatography Genesis 4μ C18 column, 4.6×50 mm

Flow rate 2.0 ml/min

Injection volume 30 μl injection into a 20 μl loop.

Gradient—starting at 95% A/5% B, rising to 95% B after 4 minutes, holding there for four minutes, then back to the starting conditions. (This may be modified if necessary to obtain better separation of peaks).

PDA detection scanning from 210 to 400 nm

Quantification of Samples

Initial examination of the sample vials containing the aqueous dilution indicates whether or not the compound is soluble in that buffer at that concentration. If it is not soluble, this should be reflected in the concentration obtained in solution by HPLC/MS. If the solution is clear, then the concentration in aqueous solvent should be similar to that in DMSO, unless degradation of the compound has occurred; this should be visible on the chromatogram.

The assumption is made that the samples will be completely soluble in DMSO, therefore the peak size obtained from that sample will reflect 100% solubility. Assuming that the dilutions of all samples have been the same, then solubility in mg/ml=(area from pbs solution/area from DMSO solution)×(original weight in DMSO solution/dilution).

Stability Assay

A typical assay that may be used to assess the stability of the compounds of the present invention is as follows. The stability of the compounds is assessed in various aqueous solutions and phosphate-buffered saline (pbs). The samples will be tested at nominal pH 2, 7.4 (pbs) and 9. These values are chosen to reflect the conditions encountered in the gut during digestion (about pH 2 up to about pH 9), and in blood plasma (nominal pH 7.4). The samples are dissolved in methanol/DMSO to prepare a stock solution. The stock solution is then diluted to give aqueous solutions at a nominal pH of 2, 7.4 and 9. Samples are analysed immediately to give initial values for purity and possible related compounds. The samples are then retained at (usually) room temperature, and re-analysed after 2 hours, 6 hours, 24 hours and 2 days (nominal).

The stability of the compounds in this aqueous buffer over the period of the test can be assessed by comparison of the chromatogram of the sample at initial with that in aqueous buffer after the given time period.

Preparation and Analysis of Samples

About 5-6 mg of the sample is accurately measured into a 4-ml glass vial and approximately 2 mls of methanol is added to it. If solution is not complete in this organic solvent, a further 0.5-1.0 ml of DMSO is added; the final solution strength should be about 2.0 mg/ml. This 2 mg/ml organic solution is then diluted 1+3 with (a) water, to use as the ‘initial’ sample, (b) very dilute HCl at about pH 2, (c) pbs at pH 7.4, and (d) very dilute NaOH at about pH 9. The pH of each dilution is then checked and noted; if not close to the desired value, the pH may be adjusted with dilute acid or alkali, as appropriate. These dilutions are made at intervals after the ‘initial’ sample, to allow for the delay due to the HPLC analysis. All samples should be diluted 50/50 with DMSO prior to injection onto the HPLC.

The samples are retained at room temperature for 2 hours initially, then sub-samples as above diluting 50/50 with DMSO prior to injection. 20 μl is injected onto the HPLC using the method shown below, injecting all samples in duplicate. The above is repeated after 6 hours, 24 hours and 2 days (nominal time intervals)

Analytical Techniques

The samples will be subjected to LC/MS using a Waters Micromass ZQ instrument (or equivalent) with test parameters typically as follows.

Waters Micromass ZQ in positive ion mode.

Scanning from m/z 150 to 900

Mobile phase A—0.1% aqueous formic acid

Mobile phase B—0.1% formic acid in Acetonitrile

Column—Jones Chromatography Genesis 4μ C18 column, 4.6×50 mm

Flow rate 2.0 ml/min

Injection volume 30 μl injection into a 20 μl loop.

Gradient—starting at 95% A/5% B, rising to 95% B after 5 minutes, holding there for four minutes, then back to the starting conditions. (This may be modified if necessary to obtain better separation of peaks).

PDA detection scanning from 210 to 400 nm

Assessment of Stability

The chromatogram peak areas of the samples at the various pH's are compared after any given time interval with those from the initial analysis at time zero. The DS peak should be quantified as a percentage of the initial sample, and the values tabulated. 

1. A compound of the formula (I):

wherein: A and B together represent an optionally substituted, fused aromatic ring; D is selected from: (i)

where Y¹ is selected from CH and N, Y² is selected from CH and N, Y³ is selected from CH, CF and N and at least one of Y¹, Y² and Y³ is N; and (ii)

where Q is O or S; R^(D) is:

wherein R^(N1) is selected from H and optionally substituted C₁₋₁₀ alkyl; X is selected from a single bond, NR^(N2), CR^(C3)R^(C4) and C═O; R^(N2) is selected from H and optionally substituted C₁₋₁₀ alkyl; R^(C3) and R^(C4) are independently selected from H, R, C(═O)OR, where R is optionally substituted C₁₋₁₀ alkyl, optionally substituted C₅₋₂₀ aryl or optionally substituted C₃₋₂₀ heterocyclyl; Y is selected from NR^(N3) and CR^(C1)R^(C2). R^(C1) and R^(C2) are independently selected from H, R, C(═O)OR, where R is optionally substituted C₁₋₁₀ alkyl, optionally substituted C₅₋₂₀ aryl or optionally substituted C₃₋₂₀ heterocyclyl; R^(C1) and R^(C2) together with the carbon atom to which they are attached may form an optionally substituted spiro-fused C₅₋₇ carbocylic or heterocyclic ring; and when X is a single bond R^(N1) and R^(C2) may together with the N and C atoms to which they are bound, form an optionally substituted C₅₋₇ heterocylic ring; and when X is CR^(C3)R^(C4), R^(C2) and R^(C4) may together form an additional bond, such that there is a double bond between the atoms substituted by R^(C1) and R^(C3).
 2. A compound according to claim 1, wherein the fused aromatic ring represented by -A-B— is benzene.
 3. A compound according to claim 2, wherein the fused benzene ring is substituted by halo.
 4. A compound according to claim 1, wherein D is selected from phenylene, fluoro-phenylene, pyridylene, fluoro-pyrdiylene, furanylene and thiophenylene.
 5. A compound according to claim 4, wherein D is selected from:


6. A compound according to claim 5, wherein D is selected from:


7. A compound according to claim 1, wherein X is selected from a single bond, NR^(N2) and CR^(C3)R^(C4) and Y is CR^(C1)R^(C2).
 8. A compound according to claim 7, wherein X is a single bond.
 9. A compound according to claim 8, wherein at least one of R^(N1), R^(C1) and R^(C2) is not hydrogen.
 10. A compound according to claim 8, wherein at least one of R^(C1) and R^(C2) is selected from C₁₋₄ alkyl.
 11. A compound according to claim 8, wherein R^(N1) is C₁₋₄ alkyl, substituted at its terminus with a carboxy, amido group or ester group.
 12. A compound according to claim 11, wherein the amino substituents of said amido group, together with the nitrogen atom to which they are attached, is cyclic.
 13. A compound according to claim 7, wherein X is N^(R2), and R^(C1), R^(C2) and R^(N2) are H.
 14. A compound according to claim 7, wherein X is CR^(C3)R^(C4), and R^(C1), R^(C2), R^(C3) and R^(C4) are H.
 15. A pharmaceutical composition comprising a compound according to claim 1 and a pharmaceutically acceptable carrier or diluent.
 16. A method of treatment of a disease ameliorated by the inhibition of PARP, comprising administering to a subject in need of treatment a therapeutically-effective amount of a compound according to claim
 1. 17. A method according to claim 16, wherein the disease ameliorated by the inhibition of PARP is selected from the group consisting of: vascular disease; septic shock; ischaemic injury, both cerebral and cardiovascular; reperfusion injury, both cerebral and cardiovascular; neurotoxicity, including acute and chronic treatments for stroke and Parkinsons disease; haemorraghic shock; inflammatory diseases, such as arthritis, inflammatory bowel disease, ulcerative colitis and Crohn's disease; multiple sclerosis; secondary effects of diabetes; as well as the acute treatment of cytoxicity following cardiovascular surgery.
 18. A method of treatment of cancer, comprising administering to a subject in need of treatment a therapeutically-effective amount of a compound according to claim 1 in combination with ionizing radiation or one or more chemotherapeutic agents.
 19. A method of treatment of cancer which is deficient in Homologous Recombination (HR) dependent DNA double strand break (DSB) repair activity, comprising administering to a subject in need of treatment a therapeutically-effective amount of a compound according to claim
 1. 